Air source heat pumps

[PlasmaParticipant @plasma]

Hi all.

I’m looking at an air source heat pump to complement my pv solar panel system.

Does anyone have any experience of these gadgets?

I’ve heard negative opinions but I’d like to hear from anyone who has one and is happy with it.

Based on the fact that gas boilers are to be posed out I’m thinking that the technology can’t be all bad.

Mick.

[Tony Pratt 1Participant @tonypratt1]

Do lots and lots of research and then do some more! YouTube will give you a flavour of the very expensive ‘gadget’ as you call them, and gas boilers being phased out gives me absolutely no confidence that air source heat pumps are the way to go.

PS I haven’t got one.

Tony

[David JuppParticipant @davidjupp51506]

Heat pump alongside solar is potentially an excellent fit.  I have both.  Replaced a very old gas boiler.  As the heat pump doesn’t actually save money (uses less energy, but in a more expensive form) I decided having solar PV + storage alongside it was key to help with the bills.

Some of the people selling these have ‘jumped on the bandwagon’, some are much more knowledgeable.

Don’t expect heat pump to be ‘fit and forget’ – will take some optimising to your building (getting the weather compensation adjusted).  Insulation for the building will have to be up to latest recommendations for you to be eligible for any grant, so that can be some additional up front expense.

Typically the heat pump will have lower peak output than a standard gas boiler – so the system dynamics, and best way to operate it are very different from a traditional boiler.

Our house has microbore pipes to most radiators – most heat pump installers refused to quote on that basis.  We found one major installer who said ‘not a problem’, and we now have a working system.

As our boiler was our only gas consumer, we’ve been able to save money by having gas meter removed (no more gas standing charge).

I suspect different manufacturer’s equipment will have different strengths & weaknesses – we have a Daikin high temperature heat pump system.  I get a bit frustrated in that it isn’t always clear quite what the system is ‘up to’, and there aren’t any logging tools to help get the system optimised.

 

[PlasmaParticipant @plasma]

Hi David.

We are having a technical survey carried out tomorrow, this is done by an independent company and basically looks at every aspect of our house from insulation to piping to glazing to room sizes etc.

This will show if we are suitable and what we need. It’s a requirement to get the boiler upgrade grant so everyone has to have one if looking to grab that £7,500 of government cash.

Our house was built in 1961 as a flat roofed bungalow,  so that roof is insulated. Then in the 80’s someone bunged a double hip roof on top of the original and that is insulated.  So we have two roofs.

It had a hot air heating system and that was replaced in the 80’s with a traditional wet system.

Hopefully adding a heat pump to the solar pv and storage will take us off the grid to all intents and purposes.

The mitsubishi system we have looked at has an app but it’s supposed to be pretty dire. Having said that I’ve got a couple of apps on my phone that reviewers said we’re rubbish, they work fine for me so maybe it’s operator error or too high expectations.

The solar system has been in two years and has been fantastic. If we have a good system for the ASHP I can’t see any problems.

There are a lot of small firms leaping from gas bashing to heat pump work as the boiler market shrinks. So finding a good installer is key.

Mick

 

 

[DiogenesParticipant @diogenes]

I was talking to a man only last weekend who does have one and was positively evangelical about it – a Panasonic unit that he’d fitted in his outbuildings – can’t remember the exact model but it looked like one of the slim units from their ‘residential’ range – https://www.aircon.panasonic.eu/GB_en/ranges/domestic/single/

I can’t remember what he said he’d saved, but it was some few hundreds – my workshop ‘accommodation’ comprises an enormous but draughty & barely enclosed farm barn, so I wasn’t paying as much attention as I should have been..

Er, d’you think this the best place to ask? 😁

[Pete RimmerParticipant @peterimmer30576]

We had two Samsung units fitted last year – a 2.5KW in the living/dining area and a 1.5kw unit in the bedroom. We only use them for summer cooling really because the dining room is a conservatory extension with solid roof which gets quite warm in summer. We bought this place with 2 solar arrays already installed and the heat pumps cost nothing to run at all, we only need them when it’s hot in summer and the solar panels easily produce enough to run them.

We picked the Samsung units because they ahve a ‘wind free’ feature which means they will provide cooling air through hundreds of holes in the casing which is a lot more comfortable than having the blower circulate, and uses less power.

I would recommend it for the cooling feature at least. We can keep the place at a very comfotable level regardless of the ambient temps. i particularly appreciate it when I get home on my bike and climb out of the sweaty bike gear staight into what feels like polar conditions.

 

 

[Speedy Builder5Participant @speedybuilder5]

If you can build up your energy into hot water storage and run your heat pump from your Pv, you are well on the way,  but it will take years before you will pay off the cost.  As others, you need to reduce your heat losses first.

If you are going down the route of a wet system, they want to replace best part of the system “more effective radiators Guv” – I would would like to see scientific evidence of that first. All they are trying to sell you is more surface area as your new system will operate at a lower water temperature. If you would tolerate a slower heat up, the old rads will be Ok.

How much sun will you get is the big issue.  SW France – no problem, NE England – do the maths.

BUT, what is the alternative ??  Add into your costs the annual service charge that checks that you are not loosing refrigerant gas.

Bob

[Bo’sunParticipant @bosun58570]

If heat pumps are an idea endorsed by the Government, I’d be somewhat wary.  Did they not say diesel was the future some time ago?

[David JuppParticipant @davidjupp51506]

Survey should give installer a good idea of best type of system, and if radiators are adequate or not.

Our survey suggested one radiator (towel rail in a bathroom) was way too small – so I replaced it with a much larger one (and included electric element for summer when the main heating is off).  Another 2 radiators were judged marginal – so we agreed ‘suck it and see’ with those.

One thing the survey won’t spot is condition of current system – turns out one of our marginal radiators is partly restricted by sludge (not noticed when the gas boiler was in use).  I’ll flush that one, then if still struggling I can replace it with a slightly larger panel.

Another element to be aware of – hot water cylinder is likely to need a larger heating coil – partly for this reason and I suspect partly to reduce site work, the Designer specified a new (pre-plumbed) cylinder.  This one included a buffer volume (related to our microbore piping), it also allowed us to move to a pressurised hot water system (a nice side benefit, but I did have to remove an existing booster pump from a shower).

We had limited possible locations for the exterior unit in the garden, the first proposals would have resulted in a huge (and very ugly) pipe run between exterior unit and the hot water cylinder.  As I knew the plumbing layout well, I was able to suggest an alternative location for the HW cylinder, cutting the length of pipe run and generally making the install simpler.  This would have been easier if the Designer had visited site – instead we exchanged things back and forth by e-mail and a couple of phone calls.

If you go forward, make sure you are clear about what installer expects you to do (or arrange) prior to the installation.  A less ‘hands on’ person than me would have been hit for some extra costs.  Also check what level of re-instatement will be done.

We used one of the bigger specialists – but that means the Designer was a long way away, the Installer was a not local sub-contractor (who brought in his own sub-contractors for extra hands on the job), could have been smoother if only one company involved.

We’ve subsequently found that the large specialist really isn’t interested in doing service work, but the heat pump manufacturer has taken that on and charges are not silly.

Overall I’m fairly happy with the system.  One error made by the installer that I’ll have to fix.  It does  take a bit more ‘management’ than the previous system, and the controller (despite having a fancy graphic screen) is less versatile than the one from my old system – but that’s likely manufacturer specific.

Do ask questions about heating vs hot water priority – we struggled for months with HW in the evenings, before eventually finding there is setting in the controller which blocked water heating for 3 hours after the last operation!  Design company wasn’t aware of this setting, eventually we got manufacturer’s Engineer to visit, who found this in a matter of minutes and changed the setting to something more reasonable.

With the grant potentially being a large chunk of the total cost, which isn’t paid until afterwards – this means that you have little or no financial leverage if there is any dispute about the install/performance after the event.  So important to be vigilant through the process.

[Robert Atkinson 2Participant @robertatkinson2]

We nned to be more precise with our descriptions. The term “air source heat pump” is only half the story. We also need to know what the “sink” is. I suspect most people are talking about air source water sink systems. This is the type you can currently get grants for. Pete Rimmer is talking about an air source air sink system. You can’t get a grant for these but they have the great advantage of providiing cooling as well as heating. This may be an option on some systems.

The issue with the air -water systems is that they generally do not provide as high a water temperature as a conventional oil or gas boiler. This means larger radiators and pipework to acheive the rate of heating. This can be an issue with poorly insulated homes.
I’ve had air – air systems for over 20 years in my current and previous properties with instant on gas water heaters for hot water backed up by an electric shower.

Robert.

[Martin ConnellyParticipant @martinconnelly55370]

I replaced my gas fired warm air central heating boiler with an air to air heat pump unit when it became obsolete. I did not have to put in radiators and the associated plumbing as a result of having suitable ducting around the house so saved half the cost of a full system that would have got some grant money from the Government. It uses half the kWh that the gas system used but they cost more per electrical kWh bought. In the coldest few weeks of the year when there is persistent below freezing temperatures I use a gas fire, but only in one room, to keep the temperature where I want it and reduce the electricity required. Mostly when the weather warms up it works fine and costs the same or less than the gas system it replaced. Additionally, as pointed out by Pete, I have the option to use cooling to keep comfortable on the three or four days a year that it is needed in the UK. My roof is at a shallow 24° and faces east and west so solar is going to be very inefficient on it, only getting about 25% of the incident sunlight a similar area would get if ideally positioned.

Martin C

[Colin BishopModerator @colinbishop34627]

Tony’s earlier post is right on the button! Do very extensive research. The effectiveness of heat pumps will depend very much on your current circumstances and the quality of expert advice you can get.

The equation is not so attractive if, in order to get lower running costs, they are dwarfed by the capital investment (long payback) needed to your property in terms of extra house insulation and maybe replacing your entire existing radiator system to obtain adequate heat output. Plus your heat pump will be running on expensive electricity rates rather than (at present) much cheaper gas rates.

In some circumstances it will work out to your advantage, especially if you have a viable solar panel backup but that isn’t always the case. A friend of mine invested heavily in solar panels but the constant weather overcast since last autumn has rendered them effectively useless.

My house was originally designed in 1965 to have gas fired warm air heating with inbuilt ducting. Unlike some of our neighbours who have converted to conventional radiator systems, we have stuck with it and currently have the latest warm air system unit with integrated hot water provided to a hot water storage cylinder.

Theoretically this is now considered to be an anachronistic system in this modern era. BUT! From the user viewpoint, it has a lot of advantages.

• The warm air system heats up the house very quickly from cold and maintains a stable temperature
• The house is open plan so only the two downstairs vents are needed to keep the whole house comfortable.
• There is always immediate hot water available from the well insulated HW storage cylinder.
• No significant electrical load is entailed and gas prices are much cheaper per KWH anyway.
• The heating unit is a condensing unit for high efficiency.
• The system is easily controllable unlike many of the complex heat pump systems which people often find difficult to balance.
• Replacing our old warm air system with the latest model took just a day and a half and fitted over the footprint of the earlier system. It included half a day extra to fit a new external balanced flue.
• And, finally, our system compares very favourably in operational costs with the more complex and expensive systems.

As an extra bonus we have a powerful gas fire in out living room which is capable of heating the entire house should there be a power cut.

The result is that we have a very effective combined heating and hot water system at a very competitive cost which has cost a fraction of what would have been the case if we had converted to a heat pump based system.

Our system won’t be applicable for everyone but  it does show that you need to do your homework and not be bamboozled by suppliers wanting to press their ‘solutions’ on your own circumstances which may not be the best overall option.

Colin

 

 

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