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Everything else / Re: Heat sand to 400F
« on: July 23, 2022, 08:51:20 AM »
Hi Veggie
Interesting point Bob makes. I'd not considered it, but when you add that to Mikes comments and have more mass at a lower temperature you get to to about where I am in my barn.
It's a single open plan room, two floors high, 9m long x 5 m wide with a poured steel reinforced concrete floor that rests on 60mm of polystyrene insulation, the depth varies but it must be about 200mm on the average. On top of that is a screed with around 130m of 16mm bore plastic pipe (PEX) in 4 different runs, around the room, none of which is in the areas under the cabinets ect. on that is the flooring, 15mm of good quality concrete tiles (with a very realistic concrete floor
So, probably an eight cubic meters mass.
I ran it in the winter, of a wood burning Rayburn cooker, which was also supplying two large cast iron radiators, two bathroom type heated towel rails and, with first call on the hot water, a 110 litre tank,
I ordered lots of aquarium type thermometers, with a 1m tail on the sensor (3/4 Euros each) and put them everywhere on the circuits so I could tell where the heat was going, not exactly, as I have no flow meters but enough to give me a good stating point for balancing the system. I also made great use of an infra red thermometer.
To cut a long story short I started with the building stone cold (February, - 10 degrees c outside, +2 inside - I was putting water under the at +30 degrees c and at the return to the boiler it was coming out at 8 / 10 degrees c. after 3 days of day time running it was coming out at around 20 c
I moved in (a domestic rebellion by me.....) and after a week I was going to bed with the downstairs at 18 degrees ans upstairs in the bedroom part at 21.
By morning downstairs was around 12 / 14 degrees, still - 10 outside. Obviously the larger part of the rise in temperature was caused by the rest of the system.
A far smaller cube of sand at 400f - around 200c, and 10 times hotter than my floor slab would do it do it but you'd have something like a large piece of furniture in the room and have to have system for recovering and distributing the heat later.
I installed the underfloor heating to 'dump' remaining heat from the water rather than as a primary heat source and it's set up in such a way that should I get around to building a small hydro generator I have a dump for the power in the early morning hours when the batteries are topped up.
In conclusion, I'd say that if you wish to use electric to build up a store of heat then I'd look at an under system for the mass and lower temperatures. Not an easy thing to retro fit I know!
The one thing I have realised from this thread is that if I do another barn conversion involving a diesel generator the exhaust will be in a trench filled with concrete under the ground floor!
I hope this gives you some real world information to work with
Cheers
Stef
Interesting point Bob makes. I'd not considered it, but when you add that to Mikes comments and have more mass at a lower temperature you get to to about where I am in my barn.
It's a single open plan room, two floors high, 9m long x 5 m wide with a poured steel reinforced concrete floor that rests on 60mm of polystyrene insulation, the depth varies but it must be about 200mm on the average. On top of that is a screed with around 130m of 16mm bore plastic pipe (PEX) in 4 different runs, around the room, none of which is in the areas under the cabinets ect. on that is the flooring, 15mm of good quality concrete tiles (with a very realistic concrete floor
So, probably an eight cubic meters mass.
I ran it in the winter, of a wood burning Rayburn cooker, which was also supplying two large cast iron radiators, two bathroom type heated towel rails and, with first call on the hot water, a 110 litre tank,
I ordered lots of aquarium type thermometers, with a 1m tail on the sensor (3/4 Euros each) and put them everywhere on the circuits so I could tell where the heat was going, not exactly, as I have no flow meters but enough to give me a good stating point for balancing the system. I also made great use of an infra red thermometer.
To cut a long story short I started with the building stone cold (February, - 10 degrees c outside, +2 inside - I was putting water under the at +30 degrees c and at the return to the boiler it was coming out at 8 / 10 degrees c. after 3 days of day time running it was coming out at around 20 c
I moved in (a domestic rebellion by me.....) and after a week I was going to bed with the downstairs at 18 degrees ans upstairs in the bedroom part at 21.
By morning downstairs was around 12 / 14 degrees, still - 10 outside. Obviously the larger part of the rise in temperature was caused by the rest of the system.
A far smaller cube of sand at 400f - around 200c, and 10 times hotter than my floor slab would do it do it but you'd have something like a large piece of furniture in the room and have to have system for recovering and distributing the heat later.
I installed the underfloor heating to 'dump' remaining heat from the water rather than as a primary heat source and it's set up in such a way that should I get around to building a small hydro generator I have a dump for the power in the early morning hours when the batteries are topped up.
In conclusion, I'd say that if you wish to use electric to build up a store of heat then I'd look at an under system for the mass and lower temperatures. Not an easy thing to retro fit I know!
The one thing I have realised from this thread is that if I do another barn conversion involving a diesel generator the exhaust will be in a trench filled with concrete under the ground floor!
I hope this gives you some real world information to work with
Cheers
Stef