Puppeteer

Author Topic: Finally, some use for excess solar power.  (Read 1049 times)

glort

  • Hero Member
  • *****
  • Posts: 2327
    • View Profile
Finally, some use for excess solar power.
« on: September 29, 2018, 11:42:18 AM »

Been wasting power boiling an urn for a while now to use some of the excess solar power I have that pushes my line voltage too high.
Today Finally found a couple of worthwhile uses.

The first one as mentioned elsewhere was to set up a Test batch Bio gas digester and use the excess solar to heat that. Probably not going to need enough heating to use much power but a few KWH I guess can be put to some sort of worthwhile use.
I thought I'll do this the clever way and boil the urn then put the hot water in progressively rather than chill the mix that has some warmth with tap water and then try to heat it all up.  That went a LOT faster than I thought.  Was soon using cold water to lower the temp of the partial fill.

The other use for the excess was Boiling the urn..... as usual. Difference was today I finally had a light bulb moment with it.

Being spring here, the garden is growing well.... as are the weeds. Everywhere. Normally I'm not too worried as the main type we get, Dandelion, is my Little Bunny's favourite. Trouble is, where he once went nuts for them, I have been giving him so much lately, he's now obviously sick of them.  It's not all he gets, still loves his Dry Mix and is OK with carrots, but the Fresh greens have definatey lost their appeal.  Maybe the kilogram a day of them that he can easily hide under I have been giving him every day is a bit of over kill?   ::)

Noticing all the weeds in the cracks of the pavers, I was going to boil up the oil burning water heater and give the weeds a scalding bath which takes good care of them roots and all and needs no chemicals. Back in the  suburbs, I would have Sprayed DDT around with no concern but now out here as a man on the land with one whole acre,   ::) I have become more fussy about things.  Well that and Bruce's heads up on the effects of so many things most of us are ignorant to with chemicals, EMF and the like.   Back there my favourite weed Killer was caustic, salt and probably some sump oil mixed in.
There is no truth at all to the malicious and unfounded scurrilous rumor that I laid waste to my Mongrel neighbors entire back yard with 150L of this stuff  couple of weeks before I left and I have NO idea how this mix got in my Diesel Fire pump and hose.   :angel:

Using my faithful urn and a 2 Kw Submersible element meant for impatient people wanting to make tea or coffee, I BOILED about 50 L of water today.
Throwing 4KW of power at 12L of water in the watering can boils it faster than I can drink a cup of coffee... so I found out repeatedly.
And doesn't it work great on the weeds!

There were a few Thistles coming along way too nicely and when I hit them with the hot water, as soon as you take the stream off the leaves, they go from Juicy green to Morbid dark gray. Everything else cooks and wilts before your eye's.
At first I was just taking water from the hot tap and I'd say it was working only because I have my heater maxed out temp wise, but it took a fair bit of water to see a change in the plants. Adding that last 20oC and boiling the water, made a BIG difference. Did this from late morning to early afternoon and walking round just before packing up for the day, I could see the weeds well and truly buggered.


The side effect of all this power consumption heating and Boiling water was really surprising.  I Made more power today than ever before AND still managed to pump more power back than I have achieved previously.  Very surprising when taking into account I bled off over 100L of hot water from the tank which was back up to temp in a couple of hours as well as everything else. Pumped about 2500L of water out the Bio storage tanks as well with the 1.5 Kw Pump which has a reasonable edge pressure wise over my 8HP petrol fire pump. I was running out of ideas of how to burn the power off short of opening all the doors in the house and turning on the AC. 

My total generation today was 75.6 KWH.  It wasn't even the most sunny day we have had in recent weeks.  Just keeping the inverters loaded I suspect kept them from throttling back and although I was burning power, I still managed to supply the house AND put an extra 24Kwh away in credit. Most days latley I can get about 14 KW back in over and above what we use. Thanks to cool nights that have still been around 3-5oC, we have had the air on at night as well.

I was happy to be able to make more power than ever and really put things to the test generation wise, but to get the high game on power back to the grid was not what I was expecting. I have been trying to use the least amount of power on the  Dummy load side but this may have been a mistake. Maybe I should be Boiling a drum of water every day and working the inverters to their max all the time?

Most I have got out my main shed array before was about 3.8 KW. Today I got that a kilo up at 4.8 on the 5.0 inverter.... which probably maxes at 4.8 knowing the way they are rated and the fact single phase systems have a 5Kw limit here.
At one point just after mid day, I had a look at all the inverters and was getting  a smidgin over 11Kw being generated.  Probably get 12kw if 3/4 of the panels were not in winter tilt still! Had half the inverters maxed out so what am I going to do with it anyway?

More to the point, what am I going to do next week? Only so many weeds I can cook and I think I'll be done by monday being a long weekend here.
Only so much dung to be kept warm.
Told the Mrs, If you want to wash in hot water,  just do it mid morning when the sun is out and not a problem. She said I never wash in hot water. I said well now at certain times if you check with me you can!

Reckon I might have to look at buying an outdoor spa. That would give me something useful to sink all this power into.
Maybe a pool.... which I could dig myself with an electric Backhoe!   :laugh:




ajaffa1

  • Hero Member
  • *****
  • Posts: 807
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #1 on: September 29, 2018, 12:09:57 PM »
Hey Glort, sorry you got the blame for poisoning your neighbors garden. Many years ago I was in a private school and fell foul of a particularly malicious teacher. He had a large garden and lawn outside his home, which he kept immaculate. I had a friend who was the son of a farmer, he supplied me with a quantity of Gromoxone (a persistent agricultural weed killer). Several days later the grass on his lawn died exposing the word WANK*R in eight foot characters. I still have no idea how that happened!  :laugh:

Bob

LowGear

  • Casey
  • Hero Member
  • *****
  • Posts: 1944
  • What? My diesel had fries for lunch?
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #2 on: September 29, 2018, 06:06:10 PM »
I'm suggesting you take the leadership of your very progressive and intelligent utilities companies and put in a Power Wall system.
NPR Tipper/Dump Truck
Kubota BX 2230
Witte BD Generator
SunnyBoy 6000 + SolarWorld 245

glort

  • Hero Member
  • *****
  • Posts: 2327
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #3 on: September 30, 2018, 05:52:51 AM »
I'm suggesting you take the leadership of your very progressive and intelligent utilities companies and put in a Power Wall system.

Why on earth would I want to do that??
I'm trying to save money on power bills not piss money up the wall!
The last thing I would do would be to buy an actual Tesla power wall. Apart from anything else the reports of problems with the things and the Big brother nature of the brand with everything haveing to be done by them by remote control would be the last thing I would ever consider.

NO battery of any kind makes financial sense for someone on grid. There are 50 Different ways of calculating saving but the simplest and only calculation is real easy. In the best possible case scenario, NONE of them will repay their investment costs in power saving over the life of the unit.
It IS that simple.

If someone wants to go on about the " Environmental" factor, again they are a dead loss.  They cannot repay their energy and emissions investment in making the things which means from that POV the world is better off with them not being built at all.

The only thing that would come near being a worthwhile Investment would be Good old lead acid Batteries int he form of Forklift packs.
They have an AH rating which would kill a powerwall and could be had for around $2500 plus charger and inverter. If you could not Do it for $8K, You'd be getting ripped off.  A power wall here, if you can get one with all Tesla's other problems, is $15K installed.  For a best possible return Of Under $5 a day at Power prices 30% above what I pay now, the numbers do not add up.

I doubt their longevity very much seeing they use the same 18650 batteries favoured by laptops  and cordless tools and Nothing I have ever owned has lasted much past 4 years before the batteries fell over badly so how they expect them to last in a daily Cycled application seems optimistic to me.
Yes they have a 10 Yr  warranty but anyone that thought tesla would still be around then is a far bigger gambling man that I am that's for sure!
Musk won't be CEO By Christmas, I'd bet he'll be gone within weeks and Tesla Surviving without him would be a Miracle. Might be a bigger Miracle to survive WITH him but the end result is the same.

The board need kicking out as well and even with competent management, the chances of the company trading  out of the massive Debt they have with repayments worth over a billion due in the next 6 Months and the market about to be hailed on with new competitive models from long established manufacturers with unlimited marketing clout and well established Brand loyalty, is beyond reality when they are still burning cash at a rate no other manufacturer is.
Tesla is already gone, the date just hasn't been announced yet. Wont be tomorrow but in the next 2-5 years..... See ya!

I have it as good as I or anyone else can ever have it right now  With my power.  I use the grid as my battery and get a 1:1 return on what I feed in.
I DO appreciate the benifit I have right now for as long as it lasts ( which sure as heck won't be that long) and anything else is just being a pedantic bitch.  I would like to have something worthwhile to do with all this excess summer power but I'm also aware I can probably shut that system down or at lest half the arrays on it and still be power positive on my spring and Autumn Consumption.

When summer comes and the AC is struggling to keep the place bearable in the 46o C days we get here, then I'll most likley be burning a lot of that power again.

LowGear

  • Casey
  • Hero Member
  • *****
  • Posts: 1944
  • What? My diesel had fries for lunch?
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #4 on: September 30, 2018, 05:34:12 PM »
8)
NPR Tipper/Dump Truck
Kubota BX 2230
Witte BD Generator
SunnyBoy 6000 + SolarWorld 245

Johndoh

  • Hero Member
  • *****
  • Posts: 536
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #5 on: September 30, 2018, 05:56:32 PM »
Musk is gone glort, are you psychic, an insider trader or VERY perceptive?
It is better to light a candle than to curse the darkness

dax021

  • Jr. Member
  • **
  • Posts: 61
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #6 on: September 30, 2018, 07:36:25 PM »
No, he's in Oz, their day starts way earlier than ours, so the news gets there first ;D

glort

  • Hero Member
  • *****
  • Posts: 2327
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #7 on: October 01, 2018, 12:07:02 AM »
I didn't do my normal Tesla news search yesterday but the writing was very much on the wall for musk being pressured to get out one way or the other. 

I don't think he is gone and probably wont be now so I'd say my prediction was in fact very wrong. He's gone as chairman but will hang around as CEO for what I now predict will be a long time. That will still allow him to play god over the company and to remain inseparably attached where as had he kept going and left to his own devices, he would have been out all together.  This deal has probably benefited him by offering an amount of protection he would not have been able to enjoy otherwise. He'll still be seen as the leader and maintain his following and the next FK up he will be able to side shift to the poor patsy who takes on the Chairman role.  Be interesting to see how long they last.  Exec's and heads of the company have been jumping ship before the office furniture they ordered gets delivered lately.

LowGear

  • Casey
  • Hero Member
  • *****
  • Posts: 1944
  • What? My diesel had fries for lunch?
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #8 on: October 01, 2018, 06:42:14 PM »
All in all he is still the man person of the 21st century with only 80 years to go before it's ended.  I can hardly wait.

I wonder if he'll be involved in another publicly traded company?  How soon before Tesla is taken back to private ownership?  I haven't heard the full bodied woman sing yet.  I agree with glort - he's not gone from Tesla yet.

Another secondary genius of this guy is the world wide super charger system.  When there are a couple hundred thousand Model 3s out there this is going to be a tidy profit center on it's own.

Oops.  This is glorts thread and I can get into a rant about Elon at the drop of a hat.

https://www.greencarreports.com/news/1119088_report-utility-survey-shows-overwhelming-support-for-renewable-power

« Last Edit: October 01, 2018, 06:46:39 PM by LowGear »
NPR Tipper/Dump Truck
Kubota BX 2230
Witte BD Generator
SunnyBoy 6000 + SolarWorld 245

glort

  • Hero Member
  • *****
  • Posts: 2327
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #9 on: October 02, 2018, 12:18:52 AM »

Oops.  This is glorts thread and I can get into a rant about Elon at the drop of a hat

I'd like to Read a rant from you.  We usually have opposing Viewpoints but you often make interesting viewpoints that challenge ones thinking and that is worthwhile in itself.

What does make me cringe is outright hero worship like I was reading on another forum where people think he can do no wrong.  They were repeatedly parroting things as fact when any time spent looking at news of the last week would verify those POV's to be flat out wrong and more than a little stupid given the information widely reported. 

Don't mind anyone having a different position, long as it's based in fact not fantasy.

One thing probably obvious to most I have learned this past 24 Hours watching the stock market, don't matter what you think of the company, whether it will be around forever or not, There is still money to be made.  I was figuring what a small investment of $10K could have yielded in tesla  under perfect  and not so difficult to pin point buy and sell times.  It would be substantial.
One report said you could have turned $1000 into 1.4M but I don't understand that being very ignorant to the ways of stock trading by and large.
None the less, Buying low and selling high even without options could have been very worth while.

With stock that bounces around like Tesla's does, I can certainly see why there is so much interest in it from all sides.
I really think the way this has played out has been a boon to musk not a punishment at all. He's skirting the terms of the settlement already and I don't see where removing him as chairman is one bit of an impediment to him. They will put in a talking head to the position whom will have musks hand firmly his his nether region controlling him like the Puppet he or she will be.  Other than that, business and controversy completely as usual.

I am still highly suspect of the EV hype.  I don't doubt for a second it will be a big market and will be the way vehicles go, that's a gaurantee just from a marketing POV. The car manufacturers have something new and exciting to give to the public whom are always excited to get new gadgetry.
How these things will work in practicality and what they will actually do for the environment as so many talk about remains very much to be seen.

Hopefully you can live to 100+ Casey to get an idea of how it pans out. The one thing I will guarantee, it probably won't be like either of us predict because like the last weeks event with Tesla, it never goes the way anyone thinks! :0)

One thing an electric car would do is solve my excess power issue.... Providing I drove a lot at night. If the Mrs took the car to work, then it wouldn't be here so useless.  Maybe I  could back feed the power back into the house after dark. Bloody expensive way to save a couple of bucks worth of power, if that. Maybe go Uber driving.... with free fuel, might be able to make up to $3 an hour once all the costs were taken into account.

Maybe I could take up pottery and use the power to Fire up an electric Kiln. Other idea was an electric Kiln for charcoal making.
What I really need is about a 100K litre vacuum thermos flask so I can heat  water all summer and use said stored heat in winter.   
OH wait! Of Course! It's obvious... need to start a POT growing operation in the garage!  Now that could be a profitable use of excess solar power!
And lets face it, even if I did get caught, the penalties are so lame I would probably not even have to do time.

Given I live  not too far from a flight path, bit of a wonder I haven't been raided already with the roofs and yard covered in panels!
 

LowGear

  • Casey
  • Hero Member
  • *****
  • Posts: 1944
  • What? My diesel had fries for lunch?
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #10 on: October 02, 2018, 09:46:34 PM »
Hi glort,

I read the whole thing.  And all by myself!  See what playing nice with others can accomplish.

The fourth quarter of the game can be the most telling and challenging.  I've lost 30 pounds in the last two years looking to downsize for the final ending.  Light players can run faster and longer.

I too got excited when Tesla went momentarily down to 260 USD.  But by the time my IRA team was on deck it was back up to 310 and is 301 this morning.

I can't believe you haven't purchased a totaled Leaf for it's batteries and made you're own storage system.  These next two years are going to be fun in the electrically powered world.  So many options.

Emotionally based stuff can be a lot of fun and exciting.  The trick is to know when you're in LaLa land.  I get tired of fake news (on all fronts) being sold as real.  There are only so many photos of the US Inaugurations.

I think the "go PV" for hot water is still being sold.  There are a number of members here on LF that heat and store  water for space heat as well as hot water only most of them use solar direct rather than losing the 10+% efficiency from changing electrical to heat propagation methods.

My fingers need a break.  How do you do it.

Aloha

NPR Tipper/Dump Truck
Kubota BX 2230
Witte BD Generator
SunnyBoy 6000 + SolarWorld 245

Johndoh

  • Hero Member
  • *****
  • Posts: 536
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #11 on: October 02, 2018, 10:38:43 PM »
I'm jealous reading this thread I couldn't generate enough power with solar here to power a digital watch! OK thats not quite true but I have talked to a few people that have solar water heaters and when you need hot water (winter) they are pretty ineffective in Ireland. I don't know if solar PV panels would be any better I somehow doubt they would provide any return on investment in Ireland no matter what the salesmen say.

With a lot of power going spare maybe it's time Glort got an electric vehicle on the road, I bet he could do it too!
It is better to light a candle than to curse the darkness

glort

  • Hero Member
  • *****
  • Posts: 2327
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #12 on: October 02, 2018, 10:51:35 PM »

I've lost 30 pounds in the last two years looking to downsize for the final ending.  Light players can run faster and longer.

You seem like the type that will last a long time. I have firmly believed for a long time that attitude is by far the biggest determination of health.
Probably explains my own position.  :embarassed:

Quote
I can't believe you haven't purchased a totaled Leaf for it's batteries and made you're own storage system.
Unlike the US, they are VERY thin on the ground here and as such, parts are a fortune.  Did look at the battery pack from a Priarse a while back but again, scarcity even though there are a reasonable number of them around now being used as Taxis as well as private vehicles, also meant the wreckers were scalping on the things.


Quote
These next two years are going to be fun in the electrically powered world.  So many options.
I sure agree with you there!

Quote
Emotionally based stuff can be a lot of fun and exciting.  The trick is to know when you're in LaLa land.

I know allright. I'm permanently in La La land. It's not a good thing.

Quote
I get tired of fake news (on all fronts) being sold as real.  There are only so many photos of the US Inaugurations.

Seems there are limitless lies and fake News about Trump though.  Nothing to do with me who the president of a foreign country is but emotion aside,
The pure and utter garbage and lies written about the man is Criminal. And it's not even about him, it's about these media organisation just manufacturing their endless crap  to garner readership.

Same with Tesla.  Obviously i'm not a fan but I don't want to read crap and lies about them either.  I do believe there is far more flag waving BS than negative but either way, Obviously fake and verifiable wrong information should not be allowed. You can do a google search every hour and just see the endlessly produced garbage churned out when there is actually no news at all, just re hashes and pontification of the same events over and over.

They literally manufacture news when there is none and they do it endlessly.

Quote
"I think the "go PV" for hot water is still being sold.  There are a number of members here on LF that heat and store  water for space heat as well as hot water only most of them use solar direct rather than losing the 10+% efficiency from changing electrical to heat propagation methods.

The big problem for me is when I need space heat, there is no spare solar available. I would have to double what I have now to make up for winter fall off. I do actually have the space for that but the waste would be it all sitting there about 8 months of the year deteriorating in the sun doing nothing. 
I'm building an oil burning heater setup for next winter and if I can remove or significantly reduce my reliance on the AC for heating, my winter consumption may be self sustainable.

I have explored the direct heating problems here and come up with some solution's for it. The thing is if you are Direct, you either have an array as a one trick pony that may be underutilized once the water is up to temp or if you then want to divert it back to an inverter, there is more complication and engineering in that than what I would consider it's worth to save the minimal inverter losses and a much more straightforward setup.

I have an on grid inverter that takes care of the water heating on it's own Virtually as it is direct coupled to the heater Circuit and is of  more than sufficent  real time output than what the heater uses. On a good day, it alone can have the water up to temp in 3 hours or less. That leaves a lot of time an array can be sitting there doing nothing if it were direct coupled which when utilised, makes up a lot more than a 10% inefficiency.
Just as a heads up, inverters have for a long time now had a lot better than 90% efficiency.  Newer ones ( 5+ years old)  are well above 95% now.
I learned that when thinking about moving the inverters inside to utilise the heat they give off... which is pretty much useless anyway because they really only warm up in summer.... again when no one needs heat.

Quote
My fingers need a break.  How do you do it.

Easy, I have no life.   :-[

glort

  • Hero Member
  • *****
  • Posts: 2327
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #13 on: October 02, 2018, 11:42:26 PM »
I have talked to a few people that have solar water heaters and when you need hot water (winter) they are pretty ineffective in Ireland.

It's the same here!
I have asked in a number of places and even the manufacturers/ retailers admit with as much positivity as they can they are not able to do much in winter. The best I can see is they would compensate for the incoming water temp drop between summer and winter.  that's not a bad thing, there is a good amount of energy to be saved there however it does not come near justifying the expense and trouble of instalation.

I asked a good friend of mine whom is a very environmentally conscious soul about his Vac tube direct system a few weeks back. I was surprised when he told me he took it down to make way for more PV because he couldn't see it gave him any benifit  for many months of the year. 
I'm just smart enough to recognize people smarter than me and I don't need to invest any time of my own in research, following their position makes me clever enough.

When I look specifically at the amount of hot water we use and it's cost in winter, I'm probably better off just putting it back on the cheaper off peak rate and being satisfied.  I pay .11C Kwh for off peak and .30C Kwh for normal power.  If I have not got the Oil heating up and running next winter which will give me enough self generated power to heat our water  I'll change the water heating back to off peak and be happy that's the best saving I can make.
The other alternative is to plumb in a pre heater and Fire that on oil. It's a less visually appealing and far more labor intensive way to go so pretty unlikely to happen.  I have run my other house for a couple of weeks on veg oil fired hot water though. Was pretty good as it was endless and the hottest water we ever had.  Would be more appealing if I could find a 400L system so I could fire it every 3 days or so and still have some heat in it but gas being quick recovery only seems to be built in smaller systems which mean any I converted would have to be fired daily which isn't always ( often) practical.


 
Quote
I don't know if solar PV panels would be any better I somehow doubt they would provide any return on investment in Ireland no matter what the salesmen say.

Always do your own numbers because the misinformation about solar both in deliberate sales hype and parroted ignorance is huge.  You would need a BIG system to cover your winter hot water AND household use. A 400L water tank requires 30 Kwh to bring the water from 15oC to 80oC.
Most people wouldn't go through 400L of hot water a day but even 200L or less allowing for heat leakage is still going to run 15Kwh which is very significant .  It's 8:15 in the morning here and I will have done more than 15KWH by 10 am  BUT, in summer, I'm often lucky to do 20 KWH on the same system for the whole day.

The thing in summer with direct water heating is much the same. Your HWS can be shut down or steaming easily by 10 am and it sits there the rest of the day doing nothing in effect. At least with PV, if the water is up to speed by 10am which is entirely practical, the rest of the day the power can be utilised for other things like AC in summer as well as other house hold loads or you can be getting some miserly amount in return if you are backfeedng to the grid.

There is also the thing of while I can do it within my skill set, it's far easier and cheaper to run wires for PV than pipes and plumbing for a direct water heating system.  Less to go wrong, less to worry about with weight loading and securing to the roof and so it goes.
You can heat a lot more water with a direct system than you can of a PV system of the same roof area but once the water is up to temp, it all becomes redundant.

Quote
With a lot of power going spare maybe it's time Glort got an electric vehicle on the road, I bet he could do it too!

I don't believe the question is Could I do it, I believe it's more a case if it's worthwhile to do it.
The answer is a resounding NO.

I could go buy a used EV but they are exy here and limited in range, size, usefulness etc.  For now and the foreseeable future, -I- would be much better doing as I have done for so long and just keep burning veg.  The  savings I could make in fueling an EV with excess solar would not return the investment and won't until EV's become a lot more popular on the used market. that's at least 20 years away to be priced with IC cars.

I looked at building an EV quite recently. Not a car exactly but an electric tractor for round here. Same components. Hugely  expensive here and then one has to take into account the certification and inspection process for a road going vehicle.  Also a lot of overhead there.

If I was to build one, I'd put a motor in every corner of the thing and make it look like a tesla  was slow!   :laugh: may still have limited range but it would get there in an impressive time!

ajaffa1

  • Hero Member
  • *****
  • Posts: 807
    • View Profile
Re: Finally, some use for excess solar power.
« Reply #14 on: October 03, 2018, 12:17:36 PM »
Hey Glort, I am curious about bio diesel. Does it have the same properties as regular diesel? What I want to know is if it as flammable as regular diesel. Thirty years ago I used to run domestic oil fired boilers on red diesel as it was tax free and cheap. These boilers had spark ignition systems that would ignite heating fuel and diesel, I doubt they would light vegetable oil but they might light Bio diesel. Another possibility would be to thin the veg with another fuel to get it to ignite.

I should point out that these boilers were all wet back systems plumbed to hot water and other heating appliances with circulation pumps. Very effective in winter but very inefficient in summer when you only need hot water.

Bob