My house has just been re-surveyed by Octopus and we have found the issue,
My original heat loss was 7.3kW and now it is 7.4kW
Sounds conclusive, but sadly not!
Our house is 98m2 and we have a 15m2 conservatory.
When the original surveyor came he immediately said that we would need to exclude the conservatory and remove the radiator so it was an unheated room. Fine.
When the heat loss calculation was done he said `good news’ we can include your conservatory as the radiator meets the heat loss. Great I thought, we have no trouble heating the conservatory and if we did it has electric under floor heating and/or we can close it off. But it has always been warm enough with GCH and currently installed radiator.
The original heat loss survey had the conservatory at a loss of about 800w and the rest of the house at 6.5kW.
That is why we have a 9kW heat pump.
The air changes are set by the MCS and represent a normal epc D rated house, ours is a B89 so the heat loss will be overstated a bit as the age of the house determines the air changes, not reality.
Today’s survey whilst coming up with the same over all heat loss got there in quite a different way.
The heat loss of the house is 5.1kW and the conservatory is 2.3kW.
Basically the conservatory represents about a third of our total heat loss, 45% of the actual heat loss. of the house.
Of course, the conservatory radiator cannot take 31% of our heat pumps output.
That is why our house is getting too hot and I cannot use the heat pump to its full potential.
It has been sized to heat our conservatory with no regard for the actual house and the heat pump cannot heat our conservatory as it is now (although it does as the heat loss is clearly too much, otherwise it would be freezing in there!)
So, how did this happen?
Our conservatory is all glass apart from a low brick wall on one side.
The original surveyor used a different construction, it magically acquired a tiled roof with an insulated loft space.
The Octopus designer would never spot this error, if they had seen the real construction and heat loss we would have had a smaller heat pump.
The rest of the calculation had errors/differences in it but it’s really every room, we think probably a failure to include the correct ceiling heights.
So my actual heat loss of my house is around what I predicted 4 to 4.5 kW.
I don’t know what Octopus propose to do or offer me to help.
The heat pump is too big and a smaller one will be just as capable of heating the conservatory as the one I have now is.
Overall a smaller heat pump seems the answer if it is offered.
Any views or thoughts are welcomed as always!