If you're going to that much trouble, keep the insulation removed beneath it and tie the boxing in insulation to the surrounding loft insulation. That makes the cold water tank part of the "warm" side of the house.
Christian.
In article , IMM writes
The tank has a jacket but is about 4' in the air on its platform which is why I thought of putting insulated panels around its open support structure, I suppose the real question is whether the insulation below needs to be still left out if the tank itself is insulated well enough
That's exactly what I'm saying. Insulate it to the level of the walls which is a U value of 0.25 to 0.35 for a place with cavity walls and insulation. That equates to 100-150mm of glass fibre, not
350mm-600mm.On an older property, the U value of the walls can easily be 2.0.
There is very little point in reducing the U value for the roof below
0.25 in the context of that..andy
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I would insulate with sheets around the platform as you describe, David. That way there is a small heat source from the house. I suppose you could put a small amount of insulation on the ceiling below the tank if you box in like this, but there is probably nothing much to be gained.
If you simply put a thicker insulation around and under the tank, it will simply reduce the rate at which the water cools in the tank when the loft is very cold. In effect you are then gambling with how long that is going to take.
.andy
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I think I am seeing your point.
Yep, my house is 250 years old, so really thick walls, but certainly no cavity.
Is there a way to find out the current heat loss through a wall?
Thanks
Dean
That us actually a good return on the investment and so should be done.
This will have a U value better than that which is for a 220mm solid brick wall with plaster. A 335mm one is at about 1.6 W/m^2.K
For other materials it's necessary to know the construction of the wall. If there are several components to it then the effect can be summed mathematically using reciprocals but if there is air inside that can make a fair difference even before insulation is added. For example for a cavity wall of two 105mm brick layers with 25mm air gap, the U value drops from 2.0 to 1.5. As soon as insulation is put into the gap it falls to around 0.5
There is a reasonably rigorous way of doing it in the Approved Document to the Building Regulations for Part L1.
There are also various references to U values on the internet if you search with Google.
If the wall is very thick, then you will also have the issue of thermal mass - in other words the amount of heat required to raise the temperature of the masonry itself. This has an impact on how quickly the air warms from cold, since to begin with, until steady state is achieved, you are also having to warm the walls. This is a separate issue but can influence heating design and controls.
.andy
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I didn't say it wasn't unless the space lost matters. That can be worth a lot more than £10 a year.
My point was that there are much larger losses of heat.
Take the same house of 7m square and 5m high. Take out 10% for windows.
The total wall area is 125 sq m.
Under the worst case conditions of temperature outside of -3 and inside of 21 degrees then the numbers work out as follows:-
Solid walls U=2.0 ===============
Heat loss = 125 x 24 x 2 = 6kW
Cavity walls with no insulation U=1.5 ==============================
Heat loss = 125 x 24 x 1.5 = 4.5kW
Cavity walls with insulation U=0.55 =============================
Heat loss = 125 x 24 x 0.55 = 1.65kW
Under the typical 10 degree average outside temperature the figures become 3.25kW, 2.44kW and 894W respectively
So looking at cavity insulation or not in the cavity wall, there is an energy saving of 1546W.
At a gas unit price of 1.4p and assuming 24*365 heating at 10 degrees outside (which was the basis of the £10-12 figure) then this comes to a saving of £190 per annum.
Typical costs for cavity insulating a house are about £1000 so the payback is in 5 years rather than the the 10-20 years of incremental loft insulation.
The difference is obvious and significant.
.andy
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Know any sheep farmers? Sheep wool is virtually worthless, unless you have
*LOTS*.Rick
You have totally missed it! Wow!
Missed it again. Look back at my post re: the upper floor/loft ceilings having a large area. That is half the house.
Don't. It is totally wrong.
If that extra costs £100, then that is 10%. very god. Then if energy costs rise then even greater return.
NO! Take a house of 7m square and 5m high and split it in two and calulate it separtely. Then adding a lot of insulation in the loft makes one half of the house, the upper floors, very cheap to run and very comfirtable in winter and summer.
If you think that, there is something wrong with your arithmetic.
.andy
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I did this assuming different upstairs temperatures. It doesn't alter the point in any significant way.
In fact if the upstairs is cooler as is typically recommended, then there is even less point in your argument because the heat loss is less anyway.
.andy
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Qualitative argument. I illustrated how greater savings and higher ROI could be achieved.
.andy
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A lot is right with the logic though.
It does!!!!!!!!!! The upstairs then is much more well insulated, warmer and consumes les fuel to heat. The upstairs room benefit greatly by heavy insulation in the loft.
You have strange logic.
You illustrated a flawed one.
I prefer to base logical argument on hard facts.
.andy
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