We'd like to remind Forumites to please avoid political debate on the Forum... Read More »
📨 Have you signed up to the Forum's new Email Digest yet? Get a selection of trending threads sent straight to your inbox daily, weekly or monthly!
UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?
Options
Comments
-
The ASHP heats the DHW to 60º - I suspect actually around 58º or something. You certainly can't hold your hand under it. Mitsubishi recommend a periodic blast with an immersion heater for anti-legionnaires, but my water seems hotter than it was before with a 3KW immersion, so I'm happy.
With regards venting heat, my view is that gas boilers heat water and then vent the excess heat to outside, so you have the heat from the boiler and the heat from the house bleeding into the atmosphere. Although the house still bleeds heat, the net result of using an ASHP is that it vents colder air back to the atmosphere - instinct tells me that must be better.
Over the next few years, my aim is to generate as much electricity as I use - not necessarily at the time I need it, just an overall balance sheet. I can only achieve that with electric heating and, of the options available in that sector, ASHPs stand out as effective solutions.
Cardew makes a good point that as I've made the purchasing decision I must convince myself I'm happy - I'm genuinely convinced that the ASHP is a better solution for my needs than an LPG gas boiler, the one remaining question being around running costs. I'm happy to be as honest about that as I can, but it will take some time for the numbers to normalise.
Cheers0 -
I can't see why that would be the case when they could have their gas boiler water temperature set to 50%
My point was that running an ASHP to give a water temperature of 50C gives a lower COP than, say, 35C.This is why heat pumps are so suited to under floor heating.
It is also a fact that some(not all by any means) people who have paid good money for a product, are less inclined to be objective in their appraisal of that product.. Even on MSE tenants(both council/HOA and private) generally are more critical of heat pumps.
To be quite honest, I do not know why, but even with clients on underfloor after changing from LPG, they say the temperature in the room is more stable. It is probably the heat curves/deltas on the pumps that moderate the temperature better. As we only deal with heat pumps and nothing else, I can only go on the comments we get here in Italy.
My honest opinion is that in the UK, too many plumbers (not all) have decided they are experts in the installation of these products and have not really got a clue. Rarely do we get a call regarding problems, as we go through everything in detail on the commissioning of the installation.
I speak as someone who bought 2 Betamax VCRs and a Toshiba HD DVD player - convinced that VHS and Blu-ray wouldn't catch on!
I worked in the electrical retail market, back in the 70's and bought VHS as it was the better system!!!
Here now it is sub zero and lovely and warm inside!!!As Manuel says in Fawlty Towers: " I Know Nothing"0 -
Meant to add - happy to give details of my installer if anyone wants it. Not sure how you can send private messages on this board - any advice on that welcome by those who want the details. I note nande2000 got a better price than me, but it proves that £7-8K for an 8.5KW system is a realistic target.0
-
not sure whether its been mentioned on here but anyone thats installing one of these should be asking their local DNO if they can. And whether their current service (electricity) can cope0
-
Diallingtone wrote: »The ASHP heats the DHW to 60º - I suspect actually around 58º or something. You certainly can't hold your hand under it. Mitsubishi recommend a periodic blast with an immersion heater for anti-legionnaires, but my water seems hotter than it was before with a 3KW immersion, so I'm happy.
With regards venting heat, my view is that gas boilers heat water and then vent the excess heat to outside, so you have the heat from the boiler and the heat from the house bleeding into the atmosphere. Although the house still bleeds heat, the net result of using an ASHP is that it vents colder air back to the atmosphere - instinct tells me that must be better.
Over the next few years, my aim is to generate as much electricity as I use - not necessarily at the time I need it, just an overall balance sheet. I can only achieve that with electric heating and, of the options available in that sector, ASHPs stand out as effective solutions.
Cardew makes a good point that as I've made the purchasing decision I must convince myself I'm happy - I'm genuinely convinced that the ASHP is a better solution for my needs than an LPG gas boiler, the one remaining question being around running costs. I'm happy to be as honest about that as I can, but it will take some time for the numbers to normalise.
Cheers
You are wasting energy on the domestic hot water temperature, reduce it to 50C. If at 58C you are having to cool it down, plus the electric boost may be cutting in. The pump will keep the temperature more constant. Ours here is set at 48C, but with the heating delta it goes to 53/54CAs Manuel says in Fawlty Towers: " I Know Nothing"0 -
not sure whether its been mentioned on here but anyone thats installing one of these should be asking their local DNO if they can. And whether their current service (electricity) can copeAs Manuel says in Fawlty Towers: " I Know Nothing"0
-
Diallingtone wrote: »... With regards venting heat, my view is that gas boilers heat water and then vent the excess heat to outside, so you have the heat from the boiler and the heat from the house bleeding into the atmosphere. Although the house still bleeds heat, the net result of using an ASHP is that it vents colder air back to the atmosphere - instinct tells me that must be better. ....
I agree with the above if you look at your household in isolation, however, when you consider that the vast clouds of vapour rising from cooling towers at powerstations represent a far greater proportion of the energy input than the waste heat from a boiler the balance changes .....
Anyway, if the ASHP has been installed and configured properly then it should perform well and, considering the cost of LPG and Heating Oil relative to natural gas, it's likely to be a far lighter on the pocket :cool:
HTH
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle0 -
Diallingtone wrote: »The ASHP heats the DHW to 60º - I suspectactually around 58º or something. You certainly can't hold your hand under it.Mitsubishi recommend a periodic blast with an immersion heater foranti-legionnaires, but my water seems hotter than it was before with a 3KWimmersion, so I'm happy.
Quote from Ecodan install manual.
As the Ecodan ASHPcan only recover a domestic hotwater cylinder to 55°
C precautions shouldbe made to raise the temperature to 60°C periodically
for pasteurisation.
However, following advice from installers and other authorities ours is setto 50c for compressor life with boost to 60c every 15 water heating cycles. May reduce DHW temp once the Immersun goes in??? Undecided at the moment.
In fact it was so cold today I couldn't be bothered to wait for the Ecodan to heat the water so pushed the boost button so the imersion would come on for 1 hour. Quite good really as the heating could continue to run.
0 -
-
jeepjunkie wrote: »
Quote from Ecodan install manual.
As the Ecodan ASHPcan only recover a domestic hotwater cylinder to 55°
C precautions shouldbe made to raise the temperature to 60°C periodically
for pasteurisation.
However, following advice from installers and other authorities ours is setto 50c for compressor life with boost to 60c every 15 water heating cycles. May reduce DHW temp once the Immersun goes in??? Undecided at the moment.
In fact it was so cold today I couldn't be bothered to wait for the Ecodan to heat the water so pushed the boost button so the imersion would come on for 1 hour. Quite good really as the heating could continue to run.
Cut the boost down from every 15 cycles, you are just wasting energyAs Manuel says in Fawlty Towers: " I Know Nothing"0
Confirm your email address to Create Threads and Reply

Categories
- All Categories
- 351.2K Banking & Borrowing
- 253.2K Reduce Debt & Boost Income
- 453.7K Spending & Discounts
- 244.2K Work, Benefits & Business
- 599.3K Mortgages, Homes & Bills
- 177K Life & Family
- 257.6K Travel & Transport
- 1.5M Hobbies & Leisure
- 16.2K Discuss & Feedback
- 37.6K Read-Only Boards