People Saying Heat Pumps are Rubbish - Are They?

matelodave

I think that as @benson1980 suggests, people put a lot more effort in analysing their leccy bills and consumption when they get a heat pump that they ever did before, when they had gas heating and cooking. They really don't know what what their combined gas and electricity consumption was in previous years because they didn't monitor it as closely.

Likewise most heatpumps now have the facility to measure their consumption in real time whereas you cant do that with gas.

IMO it gets dangerous when you give people the facility to measure or monitor something without them understanding either what is going on or without having an accurate baseline or reference to compare it with.

Same with smart meters, they see that they've chewed through 40-50kwh of leccy in a day but cant equate that with possibly their normal 10kwh or more of baseload together with the simultaneous consumption of maybe 100kwh or more of gas before they had a heatpump.

Also, many people dont understand the subtle difference between COP and SCOP.

COP is what your heatpump is achieving at the time its being measured and is therefor directly proportional to the input and output temperatures and can change by the minute and can often be higher or lower than the  SCOP figure that they think they should be achieving.

Whereas SCOP is effectively average performance determined over a much longer period (days, months or even a year) but people get hung up on a single day or even a week without actually understanding what it really means

FreeBear

matelodave said: Likewise most heatpumps now have the facility to measure their consumption in real time whereas you cant do that with gas.

Best I can do is measure the heat generated by my boiler. Doesn't tell me exactly how much gas I've used, but it is close enough to build up a picture of heat demand.

michaels

FreeBear said:

matelodave said: Likewise most heatpumps now have the facility to measure their consumption in real time whereas you cant do that with gas.

Best I can do is measure the heat generated by my boiler. Doesn't tell me exactly how much gas I've used, but it is close enough to build up a picture of heat demand.

I was the opposite, I could see half hourly usage in kwh but had no way of knowing how much heat was being produced - but as I also knew what flow temp I needed depending on outside temp it was enough info to give me a very good idea of what I would need from a heat pump (given an efficiency assumption).

benson1980

Exiled_Tyke said:

benson1980 said:

Similar experience to Spies (and others) from the looks of things. Much more comfortable house, for similar energy costs. We've just had a Powerwall installed which takes advantage of the HP tariffs thus will significantly reduce- projected payback around 7 years.

I think some of the bad press comes from both poor installs for sure, but also a significant degree of lack of consumer knowledge about their energy costs. In relation to the latter, you'll have someone complaining about their 'huge' electricity bill post install during the winter months, but will have no idea what their respective gas and electricity usage and cost was before, and that it was in fact probably around the same for that particular month. They just didn't notice or monitor it in the same way, and paid a set direct debit oblivious to how much it spikes for 3-4 months of the year.

One might also consider that there is only one way gas prices are going, at some point potentially, to encourage more take up of renewables.

I was almost caught out by this issue. Just had my mid-December electricity bill for £240 and was shocked. It was only when I checked last year's bill for the same period did I realise that is was substantially less than my previous combined gas and electricity. 

As COP worsens in colder weather I'm guessing the energy consumption 'spike' for those months could be more extreme than for gas heating?  Does anybody (particularly with a weather compensation (WD curve) set up have useful experience to share? 

Ours is a Clivet ASHP set up with homely controller, which essentially self commissions and sets up weather comp. 

Currently ticking along just under 4. When it got properly cold for a couple of days in Nov just over 3. In the milder weather in Oct it was around 5.

I should add that our installers were useless- lazy, tried to get away with cutting numerous corners, but one thing they did right was put the homely in, and one less thing for them to mess up as it does the commissioning job for them.

NedS

We have a heat pump, installed last summer in our old 1700's stone cottage. We also had additional insulation installed at the same time, but it's still nowhere near as well insulated as a modern property would be, and ours works just fine and we are really happy with it.

There are a couple things that are key to a good installation. The first is large radiators - you want to run a flow temp as low as possible, and that requires large radiators to emit the required amount of heat. Smaller radiators will equate to higher flow temps and lower efficiency / higher bills. The second thing is good flow rates are required, higher than conventional boilers.

ASHPs installs should work really well in new builds or renovations where the complete system can be replaced. Retrofitting can be a lot more difficult. One way to gauge if the current boiler system could be replaced with a heat pump is to try turning the boiler down as low as it will go and see if it is still capable of heating the house on the coldest winter days - we did this with ours, turning the old oil boiler down to 50C, and is was only just able to maintain room temperature, so we knew our radiators would need updating. However, generally just replacing an old boiler with a heat pump may not generate a great result if the rest of the system is not suitable or rubbish.

We replaced all of our radiators with larger sizes, going as large as reasonably possible in each room, balanced to the heat loss of the room. We also replaced all microbore pipe work with 22mm copper primary runs branching off in 15mm copper to each radiator. With suitably large radiators and decent pipework, we have no trouble heating the house to the desired temperature and are currently running a 35C flow temp this December. Daily COPs have been above 4, only dropping into the 3's as the temp drops into the 0-5C range.

We now have a hot water cylinder (which is cited where the old oil boiler previously resided, so now have a hot water tank instead of a combi. The ASHP takes around 30mins to reheat the tank, and we run this once or twice per day based on a timed schedule, but we can just as easily turn it on manually to top up as required if someone has a bath and empties it.

Personally I love our heat pump. No more smelly oil boiler, and the heat pump is quieter too as it's outside where I can't hear it, so only the noise of the circulation pumps running now, not the noise of the burning oil. The house is also more comfortable too, with a more consistent temperature. The oil boiler would generate temperature over-swings as the radiators would continue emitting considerable heat (at 60C) once the thermostat turned off whereas the ASHP is more able to maintain a constant room temp with far less fluctuation. There are also the green / environmental aspects - there is nothing quite like the feeling of having free heating on a cold winter's day when the sun is out and the smart meter is reading zero thanks to the solar panels on the roof. We've not had it a full year yet, bt from the data I have so far, I'm confident our bills will be lower than with the oil boiler it replaced (with oil prices comparable to gas per kWh).

NedS

Netexporter said:

Reed_Richards said:

Hoenir said:

Reed_Richards said:

I have had a heat pump for 4 years now; before that I had an oil boiler.  My heat pump keeps my house just as comfortably warm as before, but I had to replace nearly all my radiators with ones having a larger surface area as part of the installation.  Running costs have been a bit less than they were for my oil boiler but it's not made a huge difference because electricity costs a lot more per kWh than oil or gas.

What was the total cost of the installation can I ask? 

My bungalow, built in 1980, had the copper pipes that fed all the radiators buried just below the surface of the screed and unprotected.  Since this is a recipe for corrosion and eventual leaks in the long term, we took the opportunity to put new pipes in the loft to replace the existing ones.  But this made the installation need much more time and effort; it was almost like installing a complete new heating system.  So unless you want to do much the same thing there is no point in my telling you how much it cost.  It took two weeks with an average of about two people working per day.  

I had a completely new ASHP system fitted in my 1980s bungalow in two days by two blokes on the plumbing. There was a separate gang of sparkies to wire it up and install the solar PV for just over half of the second day.

I had already removed the old LPG microbore system myself, which probably saved them half a day.

Two guys installed our system in 3 days, plus the electrician was here for one day. Install included taking out old oil boiler, installing ASHP and DHW cylinder, replacing all the central heating pipe work with 22/15mm copper runs, and fitting 12 new radiators. Some of the new pipework required lifting floors and drilling through walls, which slowed them down somewhat. They would have easily been done in 2 days if they could have used more of the existing pipework rather than replacing it. Our installers were great and really knew their stuff.

QrizB

Not exactly a direct comparison, but ...

During November my 1950s 3-bed semi, heated by a conventional condensing gas boiler to 19C, used ~1000kWh of gas and ~250kWh of electricity (after deducting EV charging).

My parents detached house, roughly twice as large by floor area but built this year and heated by an ASHP to 21C, used ~500kWh of electricity.

matelodave

QrizB said:

Not exactly a direct comparison, but ...

During November my 1950s 3-bed semi, heated by a conventional condensing gas boiler to 19C, used ~1000kWh of gas and ~250kWh of electricity (after deducting EV charging).

My parents detached house, roughly twice as large by floor area but built this year and heated by an ASHP to 21C, used ~500kWh of electricity.

is that total, heating, cooking, lighting, washing etc as well as the heatpump producing hot water

QrizB

matelodave said:

QrizB said:

Not exactly a direct comparison, but ...

During November my 1950s 3-bed semi, heated by a conventional condensing gas boiler to 19C, used ~1000kWh of gas and ~250kWh of electricity (after deducting EV charging).

My parents detached house, roughly twice as large by floor area but built this year and heated by an ASHP to 21C, used ~500kWh of electricity.

is that total, heating, cooking, lighting, washing etc as well as the heatpump producing hot water

Total, as reported by their IHD.

Bendo

Probably not much of a comparison to be fair. My house was built in 2006 and seems to need the heating on constantly.

Over Christmas we are staying at bluestone in wales in one of their new build lodges. This place retains heat amazingly,  despite a double height ceiling the heat pumpnhas barely kicked in.

Makes me think my own house Persimmon forgot to insulate. Granted things will have changed in the past 20 years but the difference is crazy.