Air Source Heat Pumps

richardc1983

albyota wrote: »

Hi Richardc1983,

Even with a COP of 3 the GCH will be cheaper

Some links for fuel prices

http://www.nottenergy.com/energy_cost_comparison
http://www.energysavingtrust.org.uk/Energy-Saving-Trust/Our-calculations

You would be better off using the gas central heating, and only use the aircon for cooling, however, there may be times say in autumn and spring when the air con is more convenient for heating just a couple of rooms rather than pfaffing around with radiator valves / TRV's.

AL

Thanks for that Al. To be fair I don't have many rooms. I have a kitchen diner, this room sometimes needs the air con unit on heat for a bit when really cold as the radiator is undersized for the room but I don't mind this as when we are cooking it gets really warm and stays warm. (trv on set for 21C) There's the lounge (set for 21C) leading from the kitchen, a tiny hallway/stairs leading off from the lounge (1 small radiator at bottom of stairs) then there's the bathroom (towel rail) that doesnt have a trv fitted & 2 bedrooms both trvs are set at 19C so with the doors open the heat from downstairs means they hardly come on.

The main thermostat is fitted in the hall set at 21C day and 19C night set back so leaving the lounge door open means downstairs keeps at approx 21C then night time it doesn't drop below about 19c on a night and the heating is left on 24/7 unless we are away. The house is usually always occupied due to me working shifts so from a comfort point of view it makes sense and there doesn't seem to be much difference between cost of timed and constant. I find the house keeps at a nice level temp with the doors open and the upstairs trvs hardly ever come on. All radiators I believe other than the kitchen are oversized for the rooms and have cavity wall and loft insulation also. But for the kitchen/diner I don't mind putting the Air Con on heat for 20mins when we need to.

When I run the boiler at a higher flow temp and on timed I find that the house can drop quite cold and then still take quite a while to get comfortable again as obviously the walls floors and contents have to get back upto temperature as well. So for me I find leaving the boiler flow set point on low and constant means it just ticks over nicely with no peaks or troughs in temps. You also don't have the issue of people messing with the thermostat and setting it to 30C when the house is cold as the house is always at an even temp. Probably similar to how you would run an UFH system on a air to water system?

What do you think to this Cardew? I know you disagree with the whole is it cheaper to leave the heating on 24/7 thing but for me the difference is minimal really based on the above points.

richardc1983

zeupater wrote: »

Hi

they are pretty expensive units compared to something like the LG units which you mention above (which are also MrsZ's current favourite) ....

Z

Sent you a PM mate.

[Deleted User]

Unsure what to add about running costs but from a wear and tear point of view...

At work we have loads of Mitsubishi splits and the odd Daikin. They are used in our smaller comms/server rooms and as such run 24/7 heating or cooling depending on time of year etc. What i'm syaing is they get a hard life yet run for years with no issues and when there is an issue there is a huge support network for them. In fact they tend to out live the life of these rooms between upgrades :cool:

If it were me I'd run according to convenience - GCH when the house is occupied by wife and child. ASHP if just me Or if you have solar pv and it's a cold bright day...

Cheers

Cardew

richardc1983 wrote: »

What do you think to this Cardew? I know you disagree with the whole is it cheaper to leave the heating on 24/7 thing.

That would be better phrased as I agree with the laws of thermodynamics!

I appreciate that in your situation you want/need the heating on 24/7 and if you find the 'minimal' additional cost acceptable, so be it; I am sure given those circumstances many of us would adopt your practice.

Uclan

Heat pumps do work despite what critics may say. I replaced a cheap builder installed heat pump that didn't work and was a contendor for criticism of the product, with one that ticks all the boxes. It has a 3 year warranty- you have to pay annually or monthly with gas. It heats the house in about 30 minutes just like gas. It heats the house through the radiators- no under floor heating. It heats the hot water- four showers in the morning no problem - ashp on for 1hr twice a day to heat water- no immersion back up needed. My usage for the year- it was installed in FEB 2013 will be roughly 10-11000 kwhrs. That is my total electricity usage i.e.washing machine,lights , computers, halogen heaters. t.vs,,etc. Do not read too much into the fact that I need an electric heater. My wife likes it warm and even when the temp is as high as 24 degrees she still puts the halogen on 1 bar. As for using the ashp on 24/7- what a load of garbage. It is set to 20-21 degrees and trawls on and off when the temperature is achieved- the same as gas. The controls are similar to gas- I just up the temp stats if I need it warmer. It was installed during a cold winter and has given me no problems. The ashp is quiet and unlike the old heat pump does not need any electric back up despite temperatures last year of minus 10. The house has 4 bedrooms and is about 175+ sq. m. The walls and floors are insulated + the attic, double glazed etc.All this is achieved from one 8.5 kw heat pump. I will not name the model as I am not writing this to promote a product. The company that installed it were MCS registered and sized it correctly. Other companies recommended a larger model but the manufacturers agreed with the installer. A lot of people say gas is better. I was looking through my heating bills going back 4 years ago to a 4 bedroom property smaller than this one. I was paying 80 pounds a month for gas- 50 for electric and 62 pounds cover for my central heating + kitchen electrics with British Gas. I pay 125 pounds or less a month now and will do so until March 2015.To be honest the gas boiler was quite old but the prices 4 years ago were a lot less. Any way at present the product works for me and is far better than oil or lpg. Another factor over gas is the house is pleasantly warm throughout and we have no dry throats which was a problem with gasch, no danger of leaks or carbon monoxide poisoning.

Uclan

Heat pumps do work despite what critics may say. I replaced a cheap builder installed heat pump that didn't work and was a contendor for criticism of the product, with one that ticks all the boxes. It has a 3 year warranty- you have to pay annually or monthly with gas. It heats the house in about 30 minutes just like gas. It heats the house through the radiators- no under floor heating. It heats the hot water- four showers in the morning no problem - ashp on for 1hr twice a day to heat water- no immersion back up needed. My usage for the year- it was installed in FEB 2013 will be roughly 10-11000 kwhrs. That is my total electricity usage i.e.washing machine,lights , computers, halogen heaters. t.vs,,etc. Do not read too much into the fact that I need an electric heater. My wife likes it warm and even when the temp is as high as 24 degrees she still puts the halogen on 1 bar. As for using the ashp on 24/7- what a load of garbage. It is set to 20-21 degrees and trawls on and off when the temperature is achieved- the same as gas. The controls are similar to gas- I just up the temp stats if I need it warmer. It was installed during a cold winter and has given me no problems. The ashp is quiet and unlike the old heat pump does not need any electric back up despite temperatures last year of minus 10. The house has 4 bedrooms and is about 175+ sq. m. The walls and floors are insulated + the attic, double glazed etc.All this is achieved from one 8.5 kw heat pump. I will not name the model as I am not writing this to promote a product. The company that installed it were MCS registered and sized it correctly. Other companies recommended a larger model but the manufacturers agreed with the installer. A lot of people say gas is better. I was looking through my heating bills going back 4 years ago to a 4 bedroom property smaller than this one. I was paying 80 pounds a month for gas- 50 for electric and 62 pounds cover for my central heating + kitchen electrics with British Gas. I pay 125 pounds or less a month now and will do so until March 2015.To be honest the gas boiler was quite old but the prices 4 years ago were a lot less. Any way at present the product works for me and is far better than oil or lpg. Another factor over gas is the house is pleasantly warm throughout and we have no dry throats which was a problem with gasch, no danger of leaks or carbon monoxide poisoning.

Cardew

Uclan wrote: »

Heat pumps do work despite what critics may say. I replaced a cheap builder installed heat pump that didn't work and was a contendor for criticism of the product, with one that ticks all the boxes.

Nobody has ever argued that heat pumps do not work.

That opening sentence of your post sums up the criticism of the industry. i.e. 'you replaced a heat pump system that didn't work.'

There is no need to go over old ground as much is contained in this thread:

https://forums.moneysavingexpert.com/discussion/2968958

This was the Energy Saving Trust's conclusion on a year long trial of 29 systems.

The study found that only 13% of all sites in the trial achieved a level of efficiency the EST considers to be a 'well-performing' system, with the rest scoring below this benchmark. Ground source heat pumps were found to be slightly more efficient than air source heat pumps.


The report concluded that the worst-performing sites illustrate how customers need to be completely sure they're investing in the best system for their property and lifestyle.

At the second attempt you have a good system. People shouldn't be expected to pay many thousands of pounds for an ASHP system and take 'pot luck' that it works well.

P.S.
I have not seen any informed independent publication that suggests you should fit an ASHP is mains gas if available. I fail to see the justification for this statement 'Another factor over gas is the house is pleasantly warm throughout'

You are simply heating water for the radiators with either gas or electricity. Why would electrically heated water be better?

TiredGeek

Now take a breath.......

Air_Source_Heat_Pump_Man

It is rare that a heat pump will save you money against mains gas. The main situation where the decision is often supported is in a new build. Here the weight of building regs is pushing towards carbon savings and the heat pump can tip the balance.

Somewhat surprisingly, the RHI is looking like it will support heat pumps on gas grid homes, this will offer savings against gas but not in the order of those against oil or LPG.

From a previous point only talk to MCS accredited installers!

[Deleted User]

Since the start of the heating season it slowly dawned on me that something with the ASHP was not right...

It seemed to come ok but later in the evening it would go off and had to be manually prompted into life... Oh great just when we start to get frost :mad:

The troubleshooting begins...

Check for error codes, none.
Check all pumps are working.
Check the flow rate .
Check clocks were all synched on the wireless thermostats - they were not but after thinking it helped it did not.
Several wireless devices have been added to the house and suspected interference with the wireless thermostat.
Reboot the whole heating system, nope.
Check the wireless thermostat was linked to the base unit.
Could it be an issue with the solar immersion? But is not connected to the ASHP in any way???
A brief powercut happened around the same time, could it have caused an issue???

Ahhh... Perhaps the wireless thermostat needed new AA batteries being a few years old. Yup problem sorted, DOH!

The wireless thermostat can change the temp multiple times a day and what I think was happening by the late mid evening a temp change was scheduled it did not have enough battery to transmit over and above the other six wireless devices [current cost x2, broadband, cordless base, vodafone & EE repeaters all in the loft space but not together]. So guessing the batteries would have recovered enough to start the system in the morning...

I'm not totally finished with ruling out the mobile phone repeaters so these are still unplugged.

Well there you go that's my idiots guide and I feel like one