Air Source Heat Pump and Solar Panels

  • Starling's Avatar
    Level 6
    Hi all :)

    I am eligible for a free ASHP and solar panels, but I'm not sure if they would be right for me and my home.

    I have a 17 year old gas boiler (not condensing) and my radiators aren't all in the best condition. My house is almost 120 years old and I struggle to afford to heat it. It has a good level of loft insulation. Got a bit of wall insulation, but just the front elevation and maybe a quarter of the side wall.

    My concerns are:

    1) The cost of running the proposed new system. I realise that ASHPs are supposedly 300% efficient, but electricity is a lot more expensive than gas.

    2) Potential issues with the roof due to the age of the property and what would happen if the roof needs repairs in the future (increased costs if the solar panels need removing to access the roof).

    Does anyone have any advice or opinions on the above scenario please?

    Thanks in advance 😊
  • 26 Replies

  • Best Answer

    wizzo227's Avatar
    Level 21
    Best Answer
    Condensing boilers are almost no change; you'd still be heated from fossil gas.
    My Mitsubishi heat pump is 'not on the list' for things which the government like - it is unrecognised on my energy performance certificate but saves me more bills money than the things which are. Please try writing to them politely asking for at least the size in "kiloWatts peak rated" and preferably manufacturers' part numbers. pm me if you don't want those published all over the forum. If your roof is big then you might get enough solar on it. ??

    Are you in the type of house with heavy single layer solid stone walls ?
    Are any of your rooms bigger than you need and able to support redecorating with new 2 inch insulation board on exterior-facing walls, at least in coldest places?
    Have you got single glazed sash-windows anywhere ? Those leak too much heat and can easily be cling-filmed shut for winter.
    Are your window and door curtains adequate ?
    How many chimneys have you got and are there enough trees in the neighbourhood for offcuts to usefully contribute to your midwinter heating ?
    Have you got a '1-2-3-4-5' twisty TRV on most radiators ?
    Can you change habits to keep less rooms hot every day than was the late-20th-century usual ?
  • wizzo227's Avatar
    Level 21
    "I am eligible for a free ASHP and solar panels" sounds implausible but I'll answer your questions anyway.

    2. roof questions
    Every proper 'MCS' accredited solar panel installer puts a few hundred pounds of your money towards getting a properly qualified surveyor or structural engineer to sign off whatever needs doing to your roof to put up the solar panels, hopefully just roof hooks to rails, but they are qualified to advise if yours needs more work first. It would be most economic to do your roof repairs first while the scaffold is up and then follow with solar panels. Do everything properly and you won't ever have problems.

    1. running costs
    I'll state what I did to get minimum running costs. That differs substantially from the big whole house plus water heat pumps which most people get done, and I've had it in place for more than ten years. I have a small air to air heat pump, like an air conditioner in reverse, as pictured. It is a simpler and smaller machine which never touches the existing hot water and radiators. The blower in the living room is pictured. It was intentionally sized to be frequently able to run at nil fuel costs well inside the photovoltaic capacity of 2.5kW(peak) which I have on the roof. Even in bright-cloudy weather, I'm getting most of the electricity free; enough to supply the 0.7kW(electrical) small heat pump to deliver 1 to 2 kW(thermal) of air heating.

    3. I left in the gas combi boiler which is normally OFF. In the past 24 hours I used it for 2kWh of hot water in a few minutes and it has stayed off. To get this house to be comfortable when mostly unheated, I was careful with insulation and I don't have unnecessarily big exposed outside surface area leaking heat. In winter I'll use the old gas combi boiler central heating to radiators a little bit. The coldest day of the past five years used 30kWh of gas in 24 hours, and my gas bill last January was £1.50 per day.

    If you really are in a position to get free stuff, do think through carefully what the motives are of the generous supplier. If they are building for plumbing and jointing practice then you might get an ideal home set up out of this. Try asking for someone to look at insulation, and lifestyle, which are my biggest two gainers for heating bill. If their usual thing is spivving up the quantity of electricity which you have to buy, then get the roof done, get the solar panels, insulate, and consider whether you could skip their generous offer of a heat pump. If their offer lists part numbers I'll read datasheets and comment.

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    Last edited by wizzo227; 05-10-23 at 18:57. Reason: typo 'at'
  • Starling's Avatar
    Level 6
    Thanks for all the info @wizzo227.

    I contacted someone about a government scheme in the hope I could get a condensing boiler. They came out to assess my house and said they couldn't get the house up to an EPC rating of C by fitting a boiler, but I could have the fore mentioned system without having to contribute.

    I doubt I can just have the solar panels without the ASHP as it will only be free if they can get the EPC rating up.

    I'm feeling uneasy as I haven't been given that much information from them. Maybe they are just used to people grabbing what they can without going into the suitability of things.

    Love that little blow heater you have set up!
  • Starling's Avatar
    Level 6
    @wizzo227 Thanks for the reply; much appreciated. When considering a condensing boiler, I was just looking to improve my running costs.

    I will email them and see if I can get any info. Cheers!

    I'm in an end-terraced which is L-shaped, so a reasonably sized roof. Accrington brick walls, with a small cavity on the front elevation (the upper part has insulation boards in the cavity, as I had the outer skin rebuilt). Three of the four alcoves on the exterior walls downstairs have a type of silver insulation under the plaster board (plastic stuff with air in it).

    Fully double glazed. I only have roller blinds up (eek). Absolutely MASSIVE bay window. Chimneys taken up with two gas fires. Had a multi-fuel burner removed due to cost of fuel and up-keep. All rads have the twisty thermostats on them. My house is FREEZING. Last winter my livingroom was 8 degs C. I am home 95% of the time due to health issues, so trying to warm the house for 16 hours a day is impossible (I had the CH on for two hours a day, then had the gas fire on low in my livingroom). Not getting my violin out by the way, just being honest about my situation 😦
  • wizzo227's Avatar
    Level 21
    Thanks for the info. Your insulation sounds much improved from original, so next we want to work out where the heat is going.

    8C in the living room is no joke. The comparison figure for here; after a week away for Christmas the unheated temperature never went below 12C in frosty outside weather. Mid-terraced so I sent some heat back to next door the week after.

    The maximum improvement available from a condensing boiler is about 8% of the fuel put through the central heating gas boiler; so not that great.
    Further down I'll talk about planning to get one room toasty warm and not use the central heating much at all in the coldest week, due to the costs this year being so high. There is much more to be gained for deciding to not use certain rooms in cold conditions and to run most of your gas heating burn through one gas fire in one room which is to be your 'warm room'. The usual big whole-house heat pumps can use too much electricity at night time to save you money.

    Minimum bills is not the only consideration for choosing which room you will heat the most. Winter light from the bay window can be nice to have. Am I right that you've insulation under the plasterboard around and under several big bay windows, then fully double glazed glass occupying most of those alcoves? I could be wrong here; please do say. I'm thinking that perhaps an additional transparent layer for the winter, for improved insulation of 3/4 facets of bay windows might suit, leaving one window in the room which can still be opened. Weather is too mild this week for testing for thermal bridge cold spots (which you can feel with your hand in cold weather); photos uploaded here of what you have got might help.

    How cold does the floor get ? Some houses of that vintage are on wood rafters above an air gap, and some are on cold quarry tiles. You might want to buy a really thick rug to go with the plush curtains, just for the warm room.

    Have you got a cheap electric heater? Those are great for test because they don't blow warm air out of the chimney, for testing one room. Have you got a thermometer ? If requested I'll propose some simple tests which cost less than 50p to do and probably heat a room which you wanted to heat anyway.
    At present I am in favour of your getting the biggest allowable solar on the roof and totally avoiding boiler upgrades or heat pumps.
    Can you photograph the sunny side(s) of your roof next time it is sunny or give dimensions?
    If you can get the roof solar panels, then at times you can run a plain old electric heater for free, and that can be in the warm room too, directly decreasing your gas bill. From 2.5kW(peak) of solar panels, a sunny winter day rarely gets me more than a kW, so it is worth buying the £25 sort of "radiant" 2 small bars electric heater advertised as 800Watts/400Watts, which deliver much less heat than a gas fire on low but are still worth having because from solar power, you get some heat at nil fuel cost. I like that for nil carbon dioxide, which happens to be about the same as figuring out what will save you the most net money.

    I'd consider winter policy and decide in advance so that you will never get caught out. Suppose that you avoided the central heating but used the gas fire in one room only and as much as you like, what would that cost ? It may be that a heating policy change will help you more than the heating equipment change.

    Have a really good look at the room which is going to be your most heated room in Winter. Suppose that the rest of the house got cold but you put all efforts into there, where would all the heat from the gas fire go next?
  • Starling's Avatar
    Level 6
    Hi again @wizzo227,

    Thanks for all that!

    Last Winter I turned most of the rads right down (like number one or a bit less!). The costs per unit of gas and electric will be a bit less for me this year, but I still want to make the most of the fuel I'm using. I literally just had the central heating in low for an hour in the morning and an hour late afternoon. I had my gas fire (stove thingy) on most of the day on the lowest setting in the rear reception room.

    I have one bay window and that's only downstairs (it sticks out and has a little tiled roof). It covers the majority of the wall and is almost up to the ceiling. It has insulation directly underneath it, but not to the sides because they curve round. The window is made up of four large sections at the front, with only two small opening windows at the top.

    I have solid floors (concrete with asphalt) and laminate flooring with a plastic membrane underneath. Kitchen and hallway are tiled. I used a fan heater to warm the bathroom before going for a bath (it's safe enough due to the size of the bathroom). I have a thermometer.

    I'm sure I would have to pay for solar panels if I don't have the whole system on offer because the company won't be able to get the govt funding unless they bring my house up to EPC C rating.

    I only have the L part of the house (kitchen with bathroom above) that faces South...main roof is East and West facing.

    I have a dehumidifier which I used last Winter to help dry the air (my theory being that any heating I put on would be more efficient). The bit of CH I put on was mainly to try to stop the house getting too cold and damp!

    I very much prefer to use the rear reception room and my bedroom is above it, but that room has two doors and a less efficient gas fire. The front reception has the big bay window, but only one door and a gas fire with radiants. I will try to add a pic of the layout. Cheers!!
  • wizzo227's Avatar
    Level 21
    Thanks for that. So far I'm tentatively in favour of getting the front lounge sorted for winter, because I like the great big window for light. What's it like in there? When it was 8C, was that unheated unoccupied after you'd been mainly in the other room for a couple of days ?
    What was the date and nearest airfield airport or weather station, or how cold do you think weather had been outside that week ?

    On that plan above, which way is North, and on which side(s) are adjoining house(s)? I'd photoshop the above diagram adding grey rectangles or hatching to indicate neighbour house (much less cold than outdoors) and draw an arrow pointing North. Bins walls and hedges outside alter how exposed an exterior surface is to cold wind. I reckon that I get a tiny insulation gain from having foot thick ivy growing up my north wall, because that keeps cold wind off some of the bricks. Takes some pruning, though.

    To look at roof shape to estimate the solar photovoltaic capability, any chance of maximum zoom of a google earth satellite view, which can show trees and obstructions? EPC people tend to like the minimum to get the "has solar panels?" tickbox Y; four smallish panels near the middle of a great big roof. That is often not enough to get you best bill saving. It is possible that their generous offer to do ?£20k worth of work is going to increase not decrease usual bills by continually using electricity at night time in winter, so post here exactly what they propose before saying yes to anything.

    I'm worried about inappropriate scale of the whole house. You seem to have about 2.5x the floorspace which I do, and I consider this 2-up 2-down as about right for a man his wife and one child or me with tools and computers everywhere. As in embarassingly spacious for just me. For full occupancy and appropriate sharing of your energy bills, perhaps you should need lodgers or part-buy co-owners in order to get it up to usual temperature ?

    As I see it, the photosynthesis capacity of One Planet can support a maximum burn per person, and we should need a lot of decades of using less than that to recover from over-use in recent decades. That can only happen if your usage and bills really do go down. EPC is not the same as bill reduction because they divide the expected kWh per year by square metres of floor space. Too much floor space and exposed outdoor surface area and a good EPC rating is still too much energy needed. To move house to downsize and use much less energy can help the planet but only get the same EPC rating.

    At present I'm inclined to ask about your whole lifestyle and to start from specification of how much space you need (as oppose to have), where you want to be located (walking distance to everything which you do in a typical week?), and how many others like you in your region all have similar needs for efficient housing. It could be that there are lots more like you who's needs define a more efficient home design than what the commercial property developers have been selling recently. This is an open forum and you don't have to answer such. But to describe the ideal improves the chances that somebody might make it so.

    The plan above, though possibly suited to a family, is not suited to one person on their own because all the heat made in the kitchen goes nowhere near the front living room. In my house, much of the cooking heat is either let out by opening the kitchen window or kept in and contributes to whole house warming without using the central heat.
  • meldrewreborn's Avatar
    Level 91
    Fitting a heat pump is not going to improve the EPC any as the current EPC regime is based on energy costs, and gas is the preferred fuel. When the new EPC regime which is still being formulated comes into effect, the emphasis will be on carbon usage instead, so an electric heat pump will be favoured.

    this is a lot of house for one person, and that is the nub of the issue. Because the kitchen (and bathroom above?) is as the back and need to be accessed via the rear room I would suggest making that the preferred room for heating, especially given the bedroom above.
    The gas fires if 100% efficient woul be better to use because of the cost differential compared to electricity. Depending on the design of the gas fires a lot of the heat could be going up the chimney, but unless they are open flame effect they are still likely to be lower cost than a standard electric heater. Remember too that open gas appliances produces a lot of water vapour from combustion so the dehumidifier is a good idea.
    getting a lodger would produce largely tax free income which would more than cover the full heating cost, so it’s not something to discount too readily.
    Current Eon Next customer, ex EDF, Zog and Symbio. Don't think dual fuel saves money and don't like smart meters. Chronologically Gifted. If I offend let me know by private message, but I’ll continue to express my opinions nonetheless.