UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

rhubarbe

'Nother troll landed. Bored with this. Know what I know. Outta here.

richardc1983

rhubarbe wrote: »

If the water temp is set to 55C and the actual is 35.2 then the thing isn't working properly, period. Pipes should not be warm - our radiators feel hot to touch. Not as hot as with our old LPG boiler but then it's only costing me 25p an hour toheat the house with the Ecodan, against £1 an hour with the LPG (the boiler was old and did need changing).

Last seven days usage of electricity is 350 units, so about £32.50 for the week including cooking, lights, TV, everything in fact. Heating is on from six in the morning until eleven thirty at night.

I'm warm and saving money, even though Mr Cardew says I can't be. I love my ASHP, even though Mr Cardew says it'd be cheaper to use oil at 46ppl. I hear the sound of axes ringing: new grindstone required, methinks.

Mines more than this... damn coin meter

bushyh

Can't remember model off hand but it is their biggest domestic 7.86 watts. Will check the water flow tomorrow after work with booster - how long should booster be left on for - any ideas. As regards the electricity usage I have one convector heater which I am using for a couple of hours a day when the cold gets too much! Bizarrely the thermometer I;m using is the one I use to check legionella temperatures at work! i have just noticed there is a page in the installation instructions called optional weather compensation I wonder whether it is possible that this is not done correctly. thank god I;m at work tomorrow 1) it's warmer and 2) I won't be boring the socks off everyone. I think my plan tomorrow is to say to the builder i want them to get some independent out who knows what they're talking about regarding this and get the ball rolling.

Cardew

rhubarbe wrote: »

I'm warm and saving money, even though Mr Cardew says I can't be. I love my ASHP, even though Mr Cardew says it'd be cheaper to use oil at 46ppl. I hear the sound of axes ringing: new grindstone required, methinks.

Are your blinkers so big you can't even read?

= Cardew:

Also why are heat pumps 'far better' than oil? Granted the overall running costs are less than oil, but the installation costs are higher and arguably oil is better suited for larger properties and above all they produce very hot water for CH and HW - which is the Achilles Heel of heat pumps.

Now a new Troll(presumably zeupater?) has landed?

Your definition of a troll seems to be anyone who dares to point out that ASHPs have disadvantages as well as merit?

You demonstrate exactly what is wrong with people who buy systems and look upon any constructive discussion as a personal criticism!!!

richardc1983

bushyh wrote: »

Can't remember model off hand but it is their biggest domestic 7.86 watts. Will check the water flow tomorrow after work with booster - how long should booster be left on for - any ideas. As regards the electricity usage I have one convector heater which I am using for a couple of hours a day when the cold gets too much! Bizarrely the thermometer I;m using is the one I use to check legionella temperatures at work! i have just noticed there is a page in the installation instructions called optional weather compensation I wonder whether it is possible that this is not done correctly. thank god I;m at work tomorrow 1) it's warmer and 2) I won't be boring the socks off everyone. I think my plan tomorrow is to say to the builder i want them to get some independent out who knows what they're talking about regarding this and get the ball rolling.

I would be threatening to send them the bill when you start using fan heaters to have some sort of comfortable background temperature.

I managed to find a manual online for calorex heat pumps,

http://hainesdistribution.co.uk/pdfs/Calorex/updated%2002%20range%20manual%20apr%2009.pdf

What do you mean by how long the booster should be left on for? Do you mean you turn it on when you get home to give it a hand? I would let the booster run for half an hour before taking any readings.

Regarding the output at 0C its output is 7.86KWs @ 0C and electrical input is 3.98kw per hour. At 7C output is 11.70kws and input is 3.13kw per hour. This is with a flow temp of 55C which your system is no where near. In the specs at 0C they seem to suggest that it will achieve 55C flow temp but using more power as it goes etc.

The difference in output between 7C and 0C is nearlly a 4kws drop so if for example we are at -5C outside which is very probable we can safely assume the performance drops off again to probably somewhere between 3.5 & 4kws... so to me the system is just not able to cope with such low ambients outside and this is hence why your using 4kws an hour of electrical input to run the system. It doesnt quote figures below 0C so who knows it could be using more than 4kws per hour then factor in your booster elements and BIG electric bill to follow.

Most manufacturers give performance data which show the output of their units. They state their units work down to -15C therefore they should show the performance data down to these temps... see page 60/100 for my unit at this link...

http://mylg.co.uk/data%20for%20site/multi%20f%202008%20outdoor.pdf

It shows that if I have all three indoor units running on my system to get the full output of the system the outdoor temp would be 6C and the output of the of the unit would be 8.50KW, however at -5C the the output reduced to 6.86KW thats only a 1.64kw performance loss when the outside temp drops by 9C. Yours is losing nearlly 4kws performance when the outdoor temp drops from 7C to 0C. On mine when the outdoor temp drops from 6C-0C it loses 0.64KW of duty. Yours is massively inadequete and not upto the job at all. Ok if its a mild winter but the last 3 winters have been getting harsher and harsher.

The optional weather compensation only seems to come into affect at high ambient temps it seems to reduce the flow temp through the heating circuit. Obviously in this weather it has nothing to do with it and your system is running flat out.

The only thing you could possibly check is that ECO potentiometer switch is set to off as this seems to limit the max set point inside. However again were clutching at straws here as I doubt it is anything to do with settings at the unit.

When you go back to the builder quote what I have said above and go in with your head screwed on demonstate that you have done your investigations and they dont have a leg to stand on.

zeupater

Cardew wrote: »

Are your blinkers so big you can't even read?



Now a new Troll(presumably zeupater?) has landed?

Your definition of a troll seems to be anyone who dares to point out that ASHPs have disadvantages as well as merit?

You demonstrate exactly what is wrong with people who buy systems and look upon any constructive discussion as a personal criticism!!!

Hi

My point was quite simple .... richardc1983 raised the point that this particular make of ASHP is rated to -15C, I was simply pointing out that recent temperatures have been below this in many parts of the country, perhaps bushyh is in one of them.

This morning at around 11am the outside temperature here was still -18C, it hit -20C overnight, I talked on the phone to someone in another part of the country and it was -3C and had reached a minimum of -7C overnight .... I'm sure that exactly the same ASHP installed in both locations, whatever the make, would have performed differently.

If anyone can stand up and maintain that the COP of an ASHP doesn't fall as the outside temperature decreases, or the COP doesn't reduce as the heating circuit flow temperature increases, or as the external temperature decreases the maximum heating capacity doesn't fall, or the heating load for a property doesn't increase when the temperature difference between a constant indoors temperature and that outdoors increases (exactly the time when the ASHP COP is low) then they can, however, they should read the technical specifications of ASHPs first ......

I have read the specs, I researched extensively and considered a 15kW system with a 6kW direct coil boost and a COP of (up to) 4.0, then I decided not to install & the main reasons were cold weather performance and that you need to average a COP of around 3.0 be cheaper than gas (before allowing for the relative cost of the unit) ..... I've also looked at RHI & nobody is going to rip my gas boiler out in order for me to claim payments, my logburner is good, but it can't cope with many consecutive days at current levels of daily heating load (40C temperature difference) without something providing around an extra 150kWh ...... GSHP is probably a different story as it can cope with extremes with little loss of COP ...

Of course, the economics are different if gas isn't available .... but the weather is the same ...

HTH

richardc1983

Zeupater I agree with your comments and yes I think all areas have been below 0C unless on the coast.

Here in Leeds it didnt go above -3C all day and now its dropped to -8C my system is rated to -15C and purposely I oversized the outdoor and indoor units based on if we had very cold days.

My rooms at 5C only need about 2kws of heating however I put in 3.5kw units to give me an extra 1.5kws of heating. This works well as even though the temp is now -8C outside we still are maintaining indoor temps.

Cardew

richardc1983 wrote: »

Zeupater I agree with your comments and yes I think all areas have been below 0C unless on the coast.

Here in Leeds it didnt go above -3C all day and now its dropped to -8C my system is rated to -15C and purposely I oversized the outdoor and indoor units based on if we had very cold days.

My rooms at 5C only need about 2kws of heating however I put in 3.5kw units to give me an extra 1.5kws of heating. This works well as even though the temp is now -8C outside we still are maintaining indoor temps.

I am really confused about your flat.

You have warm air ASHP units(air to air) yet you are in a rented flat with central heating and seem to use your ASHP to supplement the central heating.

Richardc1983:=

WIth it being the weekend my landlord has the central heating on all day long. We have massive double radiators in every room and the boiler is set on max at about 80C and radiators are scalding to touch.

The house got down to 11C during the night. The heating comes on at 9am on a weekend and by 3.30pm this afternoon it had only got the house upto 20C. If I was to use the heat pump I would have hit 22C by about midday.

So for me my heat pump gets the rooms upto temp quicker in my flat quicker than the central heating and has used less energy in doing so.

richardc1983

Cardew wrote: »

I am really confused about your flat.

You have warm air ASHP units(air to air) yet you are in a rented flat with central heating and seem to use your ASHP to supplement the central heating.

I have no control over the central heating and what times it comes on as its one main system for the whole house (converted into 4 flats).

THe GCH comes on at 6-8am and then not back on till 5pm-10pm. I work nights so I am in during the day on my days off and sleeping etc. I have to use my air con in heat mode to provide heating. I used to struggle to heat one room with a fan heater, this way all my rooms are lovely and warm.

bushyh

richardc1983 wrote: »

I would be threatening to send them the bill when you start using fan heaters to have some sort of comfortable background temperature.

I managed to find a manual online for calorex heat pumps,

http://hainesdistribution.co.uk/pdfs/Calorex/updated%2002%20range%20manual%20apr%2009.pdf

What do you mean by how long the booster should be left on for? Do you mean you turn it on when you get home to give it a hand? I would let the booster run for half an hour before taking any readings.

Regarding the output at 0C its output is 7.86KWs @ 0C and electrical input is 3.98kw per hour. At 7C output is 11.70kws and input is 3.13kw per hour. This is with a flow temp of 55C which your system is no where near. In the specs at 0C they seem to suggest that it will achieve 55C flow temp but using more power as it goes etc.

The difference in output between 7C and 0C is nearlly a 4kws drop so if for example we are at -5C outside which is very probable we can safely assume the performance drops off again to probably somewhere between 3.5 & 4kws... so to me the system is just not able to cope with such low ambients outside and this is hence why your using 4kws an hour of electrical input to run the system. It doesnt quote figures below 0C so who knows it could be using more than 4kws per hour then factor in your booster elements and BIG electric bill to follow.

Most manufacturers give performance data which show the output of their units. They state their units work down to -15C therefore they should show the performance data down to these temps... see page 60/100 for my unit at this link...

http://mylg.co.uk/data%20for%20site/multi%20f%202008%20outdoor.pdf

It shows that if I have all three indoor units running on my system to get the full output of the system the outdoor temp would be 6C and the output of the of the unit would be 8.50KW, however at -5C the the output reduced to 6.86KW thats only a 1.64kw performance loss when the outside temp drops by 9C. Yours is losing nearlly 4kws performance when the outdoor temp drops from 7C to 0C. On mine when the outdoor temp drops from 6C-0C it loses 0.64KW of duty. Yours is massively inadequete and not upto the job at all. Ok if its a mild winter but the last 3 winters have been getting harsher and harsher.

The optional weather compensation only seems to come into affect at high ambient temps it seems to reduce the flow temp through the heating circuit. Obviously in this weather it has nothing to do with it and your system is running flat out.

The only thing you could possibly check is that ECO potentiometer switch is set to off as this seems to limit the max set point inside. However again were clutching at straws here as I doubt it is anything to do with settings at the unit.

When you go back to the builder quote what I have said above and go in with your head screwed on demonstate that you have done your investigations and they dont have a leg to stand on.

Really useful information which I have kept thanks. I have been on the phone to the builder today, not shouting and screaming yet but asking for the technical report being done following the visit last week. I have put in his head gas boiler/different pump scenarios but knowing that nothing will get done this side of christmas am happy (not the right word really) to wait a couple of weeks rather than people rushing into things after their Christmas parties!! Your data I intend to throw at him when the calorex report is received. Meanwhile I put the booster on at 4.30pm went to check water temp 2 hrs later - at the time the defrost setting was running and temp was at 44, once that stopped it went down to around 38, it was increasing slowly but at that point I decided I had enough of waiting in the cold! My lounge is at 15.4 which is exactly what it was on when I arrived home from work. I guess the booster isn't doing much although the outside temp. will be dropping. I am trying to avoid using the convector heater today so I can see what the meter reading is without that. Is the idea of the 55 SP temperature to have it high in the winter but lower during the milder weather so energy costs are less. My understanding was that the control panel was for the engineers rather than me and that it wasn't something to be meddled with. I am assuming there is no point in reducing that to reduce the cost if we are not getting up to that temp anyway?