ASHP or MAINS GAS?

[Nostrum]

16kw! 2 bed castle!?

its good to hear positive feedback about heat pumps after so many numpty solar p.v companies started bashing them in wrong!

 

[eaton]

Mines 118m2 1975, cavity insulated, loft insulated and double glazing about 20 years old, units using about 65% capacity! was on borderline of a 9kw but would like to add a utility, bedroom/ensuite ext in few years so went with 16 for future proofing.

 

[efficiencyman]

Yes I installed a bran new 15 Kw Dream ASHP in Sept 2012. It`s working brilliant my whole house has been so cosy, a 4 bed semi & attic conversion, with a 6 Mtr UHF conservatory and heated Koi Pond.
Well worth the capital outlay of £1,500 plumbed into my flow & return, I have the system wired to operate via an optimizer/stat. I set that to maximise the COP factor so that the ASHP does not ice over, (it costs to melt ice) when this happens the COP factor is not very good, as on all ASHP`s. That is why I use my Dream as a Hybrid when the dew point is likely cause less efficient use. The Hybrid use has enabled me to only use 20% of the gas I used on many previous years, that's now 80% of my heat coming from a more eco source, AIR. The Leccy use has not risen by very much ( I don`t think all my LED lamps have saved that much) so my outlay payback should be on track in about 4 years. The ASHP is controlled by my optimisation / stat wired so that when it`s inhibited, the Gas boiler will take over if frosty. Although the ASHP output temp is set lower, that has proved to be acceptable as I have some oversized rads & UFH thermal store, when it`s colder the gas boiler (at a higher temp) overcomes the greater heat losses. The "shoulder" months are when the COP values really pay off at 3, 4, or nearly 5 times the input Kw, so even allowing for high leccy prices over gas there is quite a good saving. Some have Mitsubishi, Toshiba or ( mine ) a Sanyo with the more efficient defrost system of a 4 way valve instead of elements to melt the winter ice. As you can tell I have had a mainly electrical career for well over fifty years so I have a relay for all zone digistats to be "ON" via the heat source in use. Many of the quotes that I had were horrendous £14 K to over £20 K for a system that is little better (if at all ) for under £2K as a pensioner I am well happy for such an efficient system. Hope you have found these comments helpful. I have No connection other than a very satisfied pensioner with a system that works well.

 

[Howsie]

On my heat loss calc it tells me the watts needed per room and then average rad size giving a % of +or- of the current rad eg
room size is
current rad size is
watts
current rad size ie 10%+
then you play around with rad sizes to get what you want ie +%

there is never an issue with over sizing! I've oversized mine to run at 45c and set heat pump to run weather comp curve to suit. Mcs only want you to prove rad size to suit that particular room, for eg my towel rail is supposedly 30% undersized yet room hits 21c at minus 4!

That won't be a towel rail then, it'll be a radiator.

 

[eaton]

1100x500 towel rail, room is 4m2 with window of 1.5m2

 

[Worcester]

That's not a room it's a shower cubicle 🙂

 

[eaton]

Its bigger than a lot others!

 

[Howsie]

1100x500 towel rail, room is 4m2 with window of 1.5m2

That doesn't heat the room at a guess.

 

[Reg Man]

That's not a room it's a shower cubicle 🙂

Sure your not thinking of 4 SQ metres, now that's what you call a shower cubical.

 

[Worcester]

That's what he said :

4m2

= 4 Sqm
Now 4m x 4m that's possibly a room = 16m2 albeit still a small one for our typical customers 🙂

 

[eaton]

2x2 and the little towell rail does its job