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

[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

 

 

[john halfpennyParticipant @johnhalfpenny52803]

We have had a Mitsubishi air to water system for 15 years. Our house was designed for it, with concrete floors upstairs and down, and underfloor heating at  roughly 30C. We are content. The system is reliable, though my research (as a precaution) shows that getting service repairs is still almost impossible. Plenty will fit new, but few will offer a repair service – even our local longstanding Mitsubishi service firm. There seems to be no expertise, apart from offering replacement. Having said that any good DIY person can do the annual checks, and there is no service required, as such. I have had a failure of the internal water store, and had to source and replace that myself. Plumbers didn’t want to know (although it was essentially a plumbing job) and the Mitsubishi agent didn’t want to know because it was a plumbing job.

What is has always worried me is the vast quantity of electronic components on the control  circuit boards, but they are in a warm benign environment, and so far trouble free. It’s the mix of electronics and water that seems so difficult for service agents to manage. I have made myself very familiar with my system, and have changed motorised valves, and could change circulation pumps if required. The only other thing which could fail would be the compressor, but changing that requires a re-gas and a specialist. I think I would likely have to change the exterior unit and the control electronics if it failed , because it is older tech now. Most probably the internal water store, circulation pumps etc could be re-used.

[PlasmaParticipant @plasma]

Hi John,

Thanks for the wealth of information about your system.

The mitsubishi has a 7 year warranty period and the firm do a maintenance contract but that looks an expensive option if nothing goes wrong.

I’m pretty good at plumbing work and actually got my gas boiler certificate several years ago (now lapsed) so I know my way round heating equipment.  Most of the gas boiler course was actually based around flues as most deaths occur from inefficient combustion or leaking flues gasses.

Take away gas and combustion and you have an inherently safe heating unit which won’t need the gas safe registration (used to be CORGI) to work on.

So I’d be comfortable learning about the unit and doing small repairs myself if they become necessary. I actually feel better being able to do my own work as some of the tradesmen these days leave a lot to be desired.

Not my house but the result of some halfwit fitting an isolation switch which they turned off before plaster boarding over it. Several other brilliant pieces of building prowess came from this firm during a house conversion that cost many thousands and left the owner with an unfinished job that i helped rescue.

 

 

[noel shelleyParticipant @noelshelley55608]

THE most important thing is the insulation of the buildings and to get older buildings to an acceptable standard is the problem. The complexity of the system, electronics and being designed for the UKs is also important. Is the government still offering grants ?

No I do not speak from experience, only observations. Noel.

[john halfpennyParticipant @johnhalfpenny52803]

I should add that our original pump failed without warning at 7 years. The local agent couldn’t diagnose the fault despite having access to Mitsubishi technical support. We were given a new unit free, but they would not say why – so maybe Mitsubishi are a good choice from a customer support perspective. Service is really just checking the pump is clear of debris, checking antifreeze concentration – hardly necessary if there are no leaks, and checking air pressure in the ch accumulators. I have done this myself, so no annual service cost in 15 years. I have changed two microswitches in motorised valves, and now keep a spare actuator on the shelf.

Our Mitsubishi Ecodan  has a car like diagnosis system, which gives basic sensor information (pressures, temps, flow etc) on a screen by selecting dipswitches – no doubt the latest systems require a plug in reader of some kind. I managed to get a detailed manual giving the switch settings from the internet.

[PlasmaParticipant @plasma]

Noel,

The government grant was £5,000 but has been boosted to £7,500 at the present time.

So for our size property that equates to just over half the system cost.

Newer version heat pumps are available that give a higher temperature output designed for older, less insulated homes. That’s not a bigger Kw unit, just higher heat output. And they cost the same price.

The early adopters of ASHP have laid the groundwork and if phasing out of gas becomes a reality then heat pumps are the preferred option.

John,

Mitsubishi seem to be the recommend manufacturer,  our work buildings all had Mitsubishi air con and heating units.

The firm I am dealing with are a large operator and seem to be doing everything right so far, with the technical and design visits pencilled in before any decisions are made.

I’m sure with amanual I will be able to deal with routine cleaning and maintenance. I’m told that these days young folk can’t change a plug or even a light bulb. My friend mentioned she was going to her 20 year old daughters house to cut her grass yesterday,  why? Because the daughter and son in law didn’t know how to lower the lawn mower deck!

Mick

 

[PlasmaParticipant @plasma]

<p style=”text-align: left;”>The surveyor came today and spent a long time measuring and recording all sorts on the house.</p>
From insulation to thermal bridging, window type and size and current radiator sizes and placement.

He said there were no issues with the property as regards having a heat pump and that there was very little we could do to improve things.

Having been built to high standards for the blown air system upgrading to a heat pump would be straight forward.

He also said the firm we were speaking to at present is a good one and definitely not like some of the players.

Mick

[PlasmaParticipant @plasma]

So.

The first company have been out to show me the design requirements for our home.

Initially they said it would need an 11Kw heat pump but upped that to 14Kw. Much bigger twin fan unit and much bigger than our current combi boiler.

Initially they said a couple of our 12 radiators would need changing, they upped that to all of them, including changing two rads for smaller ones and fitting a four panel 2.7m long radiator in the lounge. A four panel radiator is around 200mm deep!

They looked at the cylinder location and said the 200 litre one required wouldn’t fit where I want it. Neither will it go through the loft hatch.

But we can come and fit it all on monday!

Fit what? And where? More importantly how? And why is the price identical despite the changes to what I was told we would need.

Either they don’t know what they are doing or they simply don’t want the job as the house is “quirky” 1960s and they just didn’t want to say it was a pain in the neck to take on.

Either way we are not off to a great start with our governments sworn intention to get air souce heat pumps in to replace gas as soon as possible.

Another installer coming tomorrow to see what they think.

[Dave HalfordParticipant @davehalford22513]

Check the noise levels, you will run it constantly in cold weather.

[noel shelleyParticipant @noelshelley55608]

ALL the best cowboy stories are government funded – be warned ! Been there and got the sheriffs badge (cheap mazak ) Noel.

[Pete RimmerParticipant @peterimmer30576]

I can only advise extreme diligence and caution. We had several people around to quote and the results varied wildly. One thing that nearly all of them had in common was that they were unable to tell a straight story and most couldn’t hold up under even gentle scrutiny. Some offered quotes with the VAT rated at zero, which is correct, and some claimed that we didn’t qualify so they wanted me to pay them the vat which would go straight in their pocket. One even adjusted the quote to remove the VAT after I directed him to the .gov page that spelled out zero VAT if the equipment and installation were done in one package by the installer. The trouble was he simply increased the quote by the amount of VAT he had removed so the bottom line was the same. This same guy (and one of thebothers) said he was supplying Mitsubishi Electric stuff (when I asked hom specifically) but then sneakily on the quote put in cheaper Mitsubishi Heavy Industries part numbers. I’d already been warned by someone to watch out for this as one company (electric) seem to have a good reputation for parts supply and aftercare/warranty and the other poor by comparison.

In the end I found a local guy by word of mouth. He came round was very open and pleasant, gave solid advice and did a great job of installing. Ironically he was significantly cheaper than any of the other quotes I’d had.

[PlasmaParticipant @plasma]

Hi Pete,

It is indeed a bit of a minefield.

I thought that there would be a few issues as heat pumps are by no means new technology.  But the sheer volume of misinformation, miscalculation and misdirection made it feel like I was getting a quote from Donald Trump (It’ll be great, just great, too great for words,  we’ll do a great job, a big job but a great job, we’ll save you billions of dollars, just billions, it’ll be great…”

A local firm came today and presented a much clearer picture with explanation of every aspect and answers to my concerns.

They were at least 2 grand cheaper than the others and that’s before they finalise the cost of the replacement rads. By the way only two need upgrading compared to all 12 by the other companies.

The 14kw pump mentioned by the others is way too big and the complicated cylinder placement is considered a standard replacement job by this company.

On that basis we are having a system designed which they will take us through next week to ensure we are happy. After that will be a pre-installation visit by the plumbing lead to walk me through the process and sign off on the install details.

Only then will they come to do the work.

Much happier with that service level.

All posters who urged caution are correct, there are lots of cowboys responding to free government cash (I’m sure there will be a public enquiry once enough people get burned).

But there are some good firms out there. You just have to be prepared to find them.

Mick

[bernard towersParticipant @bernardtowers37738]

Hang on to them mick thats all I can say, that business is littered with boys wearing stetsons.

[PlasmaParticipant @plasma]

Absolutely Bernard!  It’s definitely the wild west out there. I will try to get a photo of the house on a new build estate close to us. The gable end had three different types of brick in it where they just opened a pack of bricks without checking and threw the wall up. Even wall paper says to check the batch numbers to make sure they all match.

I’ll update the thread when we’ve seen the design next week, but its a lot more positive than the last team who wanted to come on monday to install the system, without a clear idea of where and how they were going to fit most of the stuff.

Mick.

[Mark RandParticipant @markrand96270]

I had a number of quotes and they all seemed to calculate a heating requirement which was more than my gas boiler could produce, even before I turned it down below it’s official minimum after I installed it. It’s hard to justify a heat consumption calculation which comes to twice the customers actual gas consumption…

They all wanted to replace the radiators which I originally specified and  installed when we were planning a family and I didn’t want high temperatures. They also all wanted to replace the 2 year old hot water cylinder with ones of the same or lower specification.

I got somewhat browbeaten by SWMBO and accepted the quote of the least bad of the lot. It’s still oversized and over priced and I’m still tuning the system, but it’s done now and should pay for itself sometime around the turn of the century.

Ripped out the gas hob and put an induction one in its place last week and Octopus should be sending some lads around soon to take the gas meter away.

Now I’ve got to get more solar panels and additional battery storage 😀

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