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

loclnor

Sorry I seem to have put my query about the loft, in the wrong thread and am unable to delete it. 

matelodave

It's in the heatpump thread so probably OK. but sometimes it better to start your own thread to avoid yours getting mixed up and lost with everyone else's.
IMO heatpumps are not inherently noisier than any other sort of heating although the noise they make is different and can usually be heard outside the house rather than inside. Most gas and oil boiler nowadays have pumps and fans and will make a whining noise, some louder or more easily transmitted through the building depending on how they are installed. My heatpump has the circulating pump in a hydrobox located in our utility room and I can hear the pump running when I'm in there but that's no different to when we had a gas boiler (which in fact was worse because the fan would start and so would the pump and then a few seconds later the burner would ignite with a slight whoosh and you could hear the burner when it was lit)

I'm guessing that your EcoDan tank is festooned with pumps and valves which are going to be audible inside the house than one where the pumps are located in the external unit or even in a utility room.

I'm also guessing that there's no sound insulation or antivibration mounting under the tank and possibly the pipes are also fixed transmitting any noise a vibration to the fabric of the building . It's not the heat pump thats causing the problem, you'd have the same situation with a similar tank with mounted pumps. (pre-plumbed tanks are delivered with all the pumps and valves) It's because its a sloppy poorly executed installation. Ideally the tank should be on a solid floor if it's got pumps and stuff attached to it.

richardc1983

loclnor said:

We have had an Ecodan ASHP installed with the tanks put in the loft of our bungalow - we find it very noisy so much so that at the moment I am sleeping in the spare room as the constant whining coming from the system (think it may be the buffer tank) is making my main bedroom too noisy to sleep in. It was the installers choice to put it in the loft and they seem to have just laid boards onto the joists with nothing between the boards and the joists (apart from the normal insulation between the joists) and then put the cylinder and pipework on top of the boards. When in the loft the noise is minimal, however around the house is a different story and it can be heard all day through the ceiling. Is this correct please? - if so how do I stop the whining which is worse in cold weather. The installers seem to think the noise is acceptable. Is it me? 

Demand that they return to put insulation for sound absorption under the tanks. Explain it is affecting you being able to sleep. 

loclnor

Thank you - I expected some noise, previously we had an old oil fired boiler that used to make quite a bit of noise when it was firing up, but this is much worse as it is a high pitched revving that gets higher pitched and louder when the unit is heating water or increasing the temperature. We have two pumps and a buffer tank as well as the main tank. I really feel the noise is excessive - we have to turn the TV up to drown it out in the evening and during the day I can hear it over the radio. Anyway I will contact the installers again and see if I can get any joy from them. Thank you again. 

mrklaw

I had air conditioning fitted summer 2020 as I was fed up of those relatively short spells where the house slowly builds up heat and you can’t sleep - double so being at home instead of the nice air conditioned office. I just recently found out they heat also. I have two separate mini splits - one for the living room, one for the master bedroom. Main and ensuite bathrooms have underfloor heating, leaving only the two kids bedrooms and the spare room. 

Question - is it feasible to run these to heat the house during the winter? Currently I’m defaulting to the radiators (10 year old condensor boiler) as it heats the whole house. However the spare room is at the end of the chain so doesn’t get much heat, and I’ve never really managed to balance things so you can control temperatures individually - thermostat is in the living room which probably doesn’t help.
If its safe/practical to use these as the primary heaters during colder weather, should I consider extending that to the other bedrooms? 

Cardew

mrklaw said:

I had air conditioning fitted summer 2020 as I was fed up of those relatively short spells where the house slowly builds up heat and you can’t sleep - double so being at home instead of the nice air conditioned office. I just recently found out they heat also. I have two separate mini splits - one for the living room, one for the master bedroom. Main and ensuite bathrooms have underfloor heating, leaving only the two kids bedrooms and the spare room. 

Question - is it feasible to run these to heat the house during the winter? Currently I’m defaulting to the radiators (10 year old condensor boiler) as it heats the whole house. However the spare room is at the end of the chain so doesn’t get much heat, and I’ve never really managed to balance things so you can control temperatures individually - thermostat is in the living room which probably doesn’t help.
If its safe/practical to use these as the primary heaters during colder weather, should I consider extending that to the other bedrooms? 

At present electricity is about 5 times the cost of gas.

Even with good Air to Air Heat Pumps(ASHP) you will be pushed to get a COP of 4.0 i.e.1kWh input = 4kWh output in winter. So you are unlikely to make any savings.

matelodave

Cardew said:

mrklaw said:

I had air conditioning fitted summer 2020 as I was fed up of those relatively short spells where the house slowly builds up heat and you can’t sleep - double so being at home instead of the nice air conditioned office. I just recently found out they heat also. I have two separate mini splits - one for the living room, one for the master bedroom. Main and ensuite bathrooms have underfloor heating, leaving only the two kids bedrooms and the spare room. 

Question - is it feasible to run these to heat the house during the winter? Currently I’m defaulting to the radiators (10 year old condensor boiler) as it heats the whole house. However the spare room is at the end of the chain so doesn’t get much heat, and I’ve never really managed to balance things so you can control temperatures individually - thermostat is in the living room which probably doesn’t help.
If its safe/practical to use these as the primary heaters during colder weather, should I consider extending that to the other bedrooms? 

At present electricity is about 5 times the cost of gas.

Even with good Air to Air Heat Pumps(ASHP) you will be pushed to get a COP of 4.0 i.e.1kWh input = 4kWh output in winter. So you are unlikely to make any savings.

I'm guessing that these are Air-to-Air conditioner/heatpumps which tend to have a higher COP than Air-to-Water but you still be pushing it to get the running costs as low as gas. However as A2A heatpumps tend to be more suited to localised heating they could work out a bit more economical than running the whole central heating system. It's perfectly feasible to do it but you don't know whether its economically sensible.

In the end it's really a case of trying it out and keeping careful records of power consumption, running times, settings and temperatures (both indoors and out doors) to be able to evaluate whether there was any benefit in using them instead of the central heating. 

GGSid

mrklaw said:

I had air conditioning fitted summer 2020 as I was fed up of those relatively short spells where the house slowly builds up heat and you can’t sleep - double so being at home instead of the nice air conditioned office. I just recently found out they heat also. I have two separate mini splits - one for the living room, one for the master bedroom. Main and ensuite bathrooms have underfloor heating, leaving only the two kids bedrooms and the spare room. 

Question - is it feasible to run these to heat the house during the winter? Currently I’m defaulting to the radiators (10 year old condensor boiler) as it heats the whole house. However the spare room is at the end of the chain so doesn’t get much heat, and I’ve never really managed to balance things so you can control temperatures individually - thermostat is in the living room which probably doesn’t help.
If its safe/practical to use these as the primary heaters during colder weather, should I consider extending that to the other bedrooms? 

Should work of course. These systems are more commonly used in homes in some parts of the world, and also in offices in the UK, but they are rare in Uk homes. 

Depends what you want to achieve in the end whether this would be a good solution. You should certainly be able to  cut your energy use and carbon footprint this way, but Gas is very cheap compared to electricity, so saving money would be more of a challenge.
 
The aircon (air 2air heat pump) should be very efficient, and if you only need heat in some areas, some of the time, they offer good control and flexibility to only heat rooms where you want heat. Compared to a boiler that basically tries to heat the whole house most of the time it should be much more efficient and also more flexible. Although you'd likely need additional units unless this is just supplementary to the boiler.

Your boiler is likely around 90% efficient so 1kw gas gets 0.9 kw heat. Typical efficiency for A2A heat pump would be COP of >4, so you get >4kw of heat for each kw of electricity used. Some systems quote COP>5. That number however varies with outside temperature however. So it will be less good when outside temp is really cold, but better in mild weather.  The rub is that a kWh of electricity is generally around 5x more expensive than a kWh of gas, so you can reduce your energy use and carbon footprint, but you might not save any money. Still if you want to reduce your carbon footprint this would potentially be a good option. 

Reed_Richards

matelodave said:

AS said by others, it wont be as cheap to run as a mains gas heating system and you do need to make significant changes to the way you use it - it does not give on-demand heating like a gas boiler does. 

I see this "no on demand heating"  stated quite often but I don't see why it is true.  In fact I had a gas boiler for 20 years and that did not give on-demand heating either.
  
To heat a room rapidly you need a heat source that can put a lot more power into the room than it is losing.  So if this heating is by some form of circulating hot water you either make the water hotter than normal or you make whatever transfers heat to the room to be a higher output than is necessary but controlled by a thermostat.  The latter you will do anyway, at least insofar as it should cope with the coldest likely outdoor temperatures so most of the year is not required to run at full capacity.

My gas boiler (in my previous house) could read the room temperature, the required room temperature, the outside temperature and the flow and return water temperatures.  But I had no explicit controls to make it run harder except by turning up the set temperature of the room it monitored.  And that was only effective if the actual temperature was quite close to the set temperature so it had modulated itself down from full power.

With my heat pump I can change the target output water temperature and increase it to boost the heating.  Although this costs me money, it probably gives me more scope for on-demand heating than I had with my gas boiler.

I have radiators.  With underfloor heating you may not have the scope to boost the circulating water temperature.  But if so, that is the fault of the underfloor heating and nothing to do with the heat pump.         

Cardew

Reed_Richards said:

matelodave said:

AS said by others, it wont be as cheap to run as a mains gas heating system and you do need to make significant changes to the way you use it - it does not give on-demand heating like a gas boiler does. 

My gas boiler (in my previous house) could read the room temperature, the required room temperature, the outside temperature and the flow and return water temperatures.  But I had no explicit controls to make it run harder except by turning up the set temperature of the room it monitored.  And that was only effective if the actual temperature was quite close to the set temperature so it had modulated itself down from full power.

Don't understand the above post.

I have not seen a gas CH boiler that doesn't have a water temperature control. Typically the water temperature to the radiators can be set on a scale that corresponds from around 40C to 80+C. With weather compensation that  water temperature adjusts automatically.

On some older/cheaper boilers you don't have a separate control for the HW tank temperature.

An ASHP is more efficient at low water temperatures. and is typically operating in the range 30C to 40C to larger radiators of under floor heating.