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

bushyh

Sorry guys suggested reply for perusal and comment - please (beg)

Unfortunately I am not yet at the stage that I agree with the course of action proposed.

The fact that a proposal has been put forward to change the refrigerant and run an immersion system I consider to be a clear admission that the pump is undersized. If a pump of sufficient capacity had been installed there should not be any problems even in extreme weather and there would be no need to have a booster installed. I quote 'As well as heating your home Calorex heat pumps are uniquely designed to supply hot water at 65C without the need for electric heating back up'(page 4 of their brochure). My assumption until proven otherwise is that the immersion will add to the cost of running the system perhaps up to £20 a month. When temperatures go below freezing will the frost stat result in the immersion being on permanently and adding further to the cost? Will the booster if only on for 2 hours a day give the heat needed for the rest of the day once it has dissipated from the system? Under your proposed scheme what categorical assurances and formal guarantees would be given regarding temperature, efficiency and running costs as well as the impact that changing the refrigerant will have on the life of the pump - will this not place additional stress on the compressor? (Incidentally the pump unit already has external rust). On page 30 of the technical manual it clearly states that electrical resistance heaters used to upgrade the temperature (and I presume this is what the proposed immersion is designed to do) dramatically reduces efficiency and increases running costs. Furthermore it goes on to say that the Calorex heat pumps are very energy efficient provided that care is taken matching the heat pump and space heating system with the property and so I come back to the point that it is in the matching that we have a problem.


I maintain my stance that what is required is an independent review of the house size and system installed.

The discussions held with QTS and Calorex indicated that the radiator specification (and I am assuming at this stage these are of sufficient size for the house) required around 7 watts to operate effectively. The data in the Calorex brochure for air to water shows this is clearly achievable at a temperature of 7C, but only just about viable at 0C. Given the figures were that tight I ask whether any real consideration was given to how this system would operate at low temperatures. Which other operating systems were considered and why did you choose to install the Calorex pump? The temperatures experienced recently are not uncommon in the UK albeit the sustained period for which we had them was. I have looked at capacity for a couple of other pumps - The Ecodan HW140V appears to still give 11 watts of capacity at -15C at 14 watts at 0C, going to get figures for others.

I attach again the meter reading and temperature detail records maintained previously, these act as a reminder of quite how miserable it has been for us during the cold period. Having guests sat in scarves for Christmas lunch, having to wear 3 jumpers and buy electric blankets to keep warm is not what you expect when you purchase a new house.


In conclusion the capacity reduction on the Calorex unit is very high and I do not feel enough consideration was given to this when designing the system. Had a pump that was fit for purpose been installed then we would not be looking for solutions to boost the output of the Calorex in situ. I remain of the view that either the unit or the heating system should be changed and I will over the next few days be putting together some information to forward to the NHBC, planning department and my solicitor.

albyota

I've just made a couple of adjustments in red, Good Luck.

bushyh wrote: »

Sorry guys suggested reply for perusal and comment - please (beg)

Unfortunately I am not yet at the stage that I agree with the course of action proposed.

The fact that a proposal has been put forward to change the refrigerant and run an immersion system I consider to be a clear admission that the pump is undersized. If a pump of sufficient capacity had been installed there should not be any problems even in extreme weather and there would be no need to have a booster installed. I quote 'As well as heating your home Calorex heat pumps are uniquely designed to supply hot water at 65C without the need for electric heating back up'(page 4 of their brochure). My assumption until proven otherwise is that the immersion will add to the cost of running the system perhaps up to £20 a month. When temperatures go below freezing will the frost stat result in the immersion being on permanently and adding further to the cost? Will the booster if only on for 2 hours a day give the heat needed for the rest of the day once it has dissipated from the system? Under your proposed scheme what categorical assurances and formal guarantees would be given regarding temperature, efficiency and running costs as well as the impact that changing the refrigerant will have on the life of the pump - will this not place additional stress on the compressor? (Incidentally the pump unit already has external rust). On page 30 of the technical manual it clearly states that electrical resistance heaters used to upgrade the temperature (and I presume this is what the proposed immersion is designed to do) dramatically reduces efficiency and increases running costs. Furthermore it goes on to say that the Calorex heat pumps are very energy efficient provided that care is taken matching the heat pump and space heating system with the property and so I come back to the point that it is in the matching that we have a problem.


I maintain my stance that what is required is an independent review of the house size and system installed.

The discussions held with QTS and Calorex indicated that the radiator specification (and I am assuming at this stage these are of sufficient size for the house) required around 7 KiloWatts to operate effectively. The data in the Calorex brochure for air to water shows this is clearly achievable at a temperature of 7C, but only just about viable at 0C. Given the figures were that tight I ask whether any real consideration was given to how this system would operate at low temperatures. Which other operating systems were considered and why did you choose to install the Calorex pump? The temperatures experienced recently are not uncommon in the UK albeit the sustained period for which we had them was. I have looked at capacity for a couple of other pumps - The Ecodan PUHZ-HW140VHA2 appears to still acheive 11 KiloWatts of capacity at -15C at 14 KiloWatts at 0C, going to get figures for others.

I attach again the meter reading and temperature detail records maintained previously, these act as a reminder of quite how miserable it has been for us during the cold period. Having guests sat in scarves for Christmas lunch, having to wear 3 jumpers and buy electric blankets to keep warm is not what you expect when you purchase a new house.


In conclusion the capacity reduction on the Calorex unit is very high and I do not feel enough consideration was given to this when designing the system. Had a pump that was fit for purpose been installed then we would not be looking for solutions to boost the output of the Calorex in situ. I remain of the view that either the unit or the heating system should be changed and I will over the next few days be putting together some information to forward to the NHBC, planning department and my solicitor.

richardc1983

Bushyh,

Abyota's version is spot on I was about to make the same adjustments.

YOu also need to point out that your house didnt get above 16C considering the ammount of money you have spent on electricity you have been cold at temps approaching 0C whilst your neighbours have received similar bills for gas but have been toasty warm. The heat pump should have given you lower bills if it was designed properly.

Also state that if they start adding booster heaters and these are running when temps drop below 0C then your bills are going to go up even further than they are now... yes you might be warm when the booster heaters are running but your paying the cost of running 2 outdoor units on top of the current bills you have!

Put the wind up them and dont back down the system and suggestions to improve them are shoddy. I would be straight to a solicitor.

bushyh

I spoke to builder this morning just to clear air about what I meant by botch job. It was a useful conversation and built a few bridges. Behind the scenes he is getting quote for installing gas boiler and taking away pump. I think by the end of the quite amenable conversation he understood that I felt he had been badly advised by what pump to install, that the pump is doing what it says on the packet so why try and make it what it is not. I would say that he was not aware of the capacity figures of other units so once I have got that data I will send email perhaps toning down the last bit for now. He won't put in a replacement pump but I think he may well go the boiler route which I am happy with.

richardc1983

bushyh wrote: »

I spoke to builder this morning just to clear air about what I meant by botch job. It was a useful conversation and built a few bridges. Behind the scenes he is getting quote for installing gas boiler and taking away pump. I think by the end of the quite amenable conversation he understood that I felt he had been badly advised by what pump to install, that the pump is doing what it says on the packet so why try and make it what it is not. I would say that he was not aware of the capacity figures of other units so once I have got that data I will send email perhaps toning down the last bit for now. He won't put in a replacement pump but I think he may well go the boiler route which I am happy with.

A comment has been posted over on one of the other forums I posted this in for you.

Something we didnt think of is that this calorex heat pump is a fixed speed compressor it will therefore have fixed speed fans. These units are not designed to work much below 5C.

All the other units that have been reccomended are inverter systems.

When you say he may well go for the boiler route do u mean he will fit a gas boiler in addition to the heat pump you already have? Or rip out the system completly?

thechippy

Rich,

She means they will remove the hp and convert to full gch.

Having fixed speed compressors does not always mean fixed speed fans. It would not really apply too much in this case anyway, you need to move the air quickly over the coil. With regard to inverters, if the system is undersized, the inverter compressor would run flat out anyway, as the system demand won't fall to allow it to ramp down...;)

The problem here, is the system is half the required capacity and not rated below zero anyway. She needs a system that is capable of at least 14kw down to -10 or below.

Bushy,

If you can get your guy to remove the hp and use a gas boiler instead, then that is the best route. Probably cheaper for him as well.

bushyh

You are right chippy in that the talk is to rip out existing pump and use gas only. Strange thing is I after all this info and research I'll almost be disappointed not to have a good asp albeit I'll be glad to be warm and rid of the monster machine. We will see what next week brings - hopefully an on-line party:j

thechippy

....Nice one,

I hope we are all invited......:beer:....;)

richardc1983

thechippy wrote: »

Rich,

She means they will remove the hp and convert to full gch.

Having fixed speed compressors does not always mean fixed speed fans. It would not really apply too much in this case anyway, you need to move the air quickly over the coil. With regard to inverters, if the system is undersized, the inverter compressor would run flat out anyway, as the system demand won't fall to allow it to ramp down...;)

The problem here, is the system is half the required capacity and not rated below zero anyway. She needs a system that is capable of at least 14kw down to -10 or below.

Bushy,

If you can get your guy to remove the hp and use a gas boiler instead, then that is the best route. Probably cheaper for him as well.

WHat I meant was that inverter compressors are able to work to colder temperatures as they work differently and are more efficient.

Ive never seen a fixed speed system that is guaranteed to work down to -15C.

thechippy

A fixed speed can work down to low ambients just as well as an inverter.

An inverter compressor is simply a compressor who's speed can be varied by the inverter board, so it can ramp down as the load reduces, or increase as the load rises.

There is no difference in the efficiency of each as such, it's just the way they are controlled.

The better manufacturers use inverter systems, as when correctly applied are more efficient than fixed speed as they match the load to that required. As the load either increases or decreases, the compressor will try to match the load required. This is more efficient than a simple on/off scenario of anything fixed speed.

It's the same as modern boilers that use a modulating gas valve. The boiler will ramp up/down as required by the load.