Ground/Air sourced Heat pumps

[Jo]

I have been investigating Air/Ground sourced heat pumps. This is the results of my investigations:

Installation of Ground array (digging up garden to 5m depth to put in "slinky"), Heat pump, extra tanks etc, replacing radiators with bigger ones and taking up all of my floors to install 22mm pipes = £25K What they did not mention was:

Annual service: £250
Bi-annual re-gassing: +£195 (can't see why this is any different to getting the car re-gassed which costs £45)

Ground array is expected to last 20 years, Heat exchanger (heat pump) 10 to 20 years

If I want "hot" water"# I need to run an emersion as well 



So taking the 20 years as guaranteed that is £1,600 a year "ownership" costs (ignoring the disruption of installation) plus running costs.... Ground is 1/4 of heating by electric, Air sourced is 1/2 heating by electric costs... 



Current annual electric costs for night storage heaters and annual electric = £500 (was £400 but the price went up 22% at the end of August  ). I have no gas to the property, heat the house with night storage heaters (mid winter = 7 hours * 1.5KW = £1.5 a day) plus burn free wood on my log burner... currently sweltering at 25 degrees due to using log burner, which was also working well kicking out heat last tuesday when we had a power cut  .


When do you think I will be installing the heat pump?

Jo

[Jock McFarlane]

You forgot to estimate the cost of running the electric pump which I believe is considerable.

[Jo]

Yes the factor for ground sourced is 1:4 (pump vs straight electric if not demanding too hot an output) and air sourced at best 1:2.5. Not forgetting under 0 degrees both do not work at all well. Thankfully this coming week I will have my log burner working


Jo

[coniston]

I'm glad someone has an interest in this, thanks Jo. My background is 40 years working in design of mobile air conditioning and transport refrigeration. I am flabbergasted at the miss truths being spread around about heat pumps (by the companies selling them mostly). I listened to a short bit on Jeremy Vine on radio 2 a couple of days ago, the guy extolling the virtues of heat pumps was clearly reading from the book of sales lies.

Any compression refrigeration cycle (reverse heat pump or cooling) has a constantly varying Coefficient of Performance) CoP, yes they can achieve 4 even air source ones but only under certain conditions which are usually to high a temperature to be of any use i.e. not in cold weather. The guy on radio 2 was quoting a refrigerant IIRC R32 that evaporates at -32C, well R134a typically used until recently in most car AC systems and others evaporates at -26C but still doesn't produce any real heat below 0C ambient air temperature.

The costs at the moment are prohibitive and this guy seemed to think a simple replacement would only take 2 days and not need to change the radiators and pipework, what utter rubbish as the water flow rate has to be much higher so bigger pipes and bigger radiators as the temperature difference is lower due to the water temperature being lower something like 40C compared to gas heating being 60 - 65C.

The maths doesn't add up wither for cost or performance. Maybe on new build houses that are well insulated but not on older properties which cannot be insulated to higher standards due to their construction. I am against cavity wall insulation in some houses as this can lead to greater condensation particularly if the only air bricks / vents are below floor level and same goes for this spray on roof insulation.

We will be changing to a combi boiler next year before they get banned for replacement installations.

Rant Rant Rant.

Chris

[jon38r80]

I was constantly having M&E consultants pushing air source heating and I was never convinced that they were the 'magic' solution they pushed. they are after all only fridges working backwards and can only pull the available heat from the air outside which is pretty cold in winter so they have to work pretty hard in terms of the pumpenergy consumption so I dont get the 'efficient' bit of the argument. Seems to me its more about that we now have to import our gas not sucking it out of the North Sea.
Im open to enlightenment though.

[dscott]

NO.

[dscott]

The first job in the house 9 years ago was to insulate under the floor. Then put over boards.
Then replace the inner front door. And slowly do all the windows.
Solar panels put in after I re worked the rear roof. Last needed heat for hot water back in February.
Next insulate the front roof and rebuild the chimney. Our pot is blanked off. We are the last house to keep snow on it.
Took the tiles off the front and have 100 mm of Selotex and a cover of multifoil. Heat run once last week for hot water as the solar panels failed. Met office switched the sun down for several days.
Currently just finished the insulating the lower front wall and putting the wall back further out.
Also working on a new back door and insulating round it. Today discovered even more MID 70s Builders missing insulation round where the sink is. Kitchen extension will be made smaller on the inside with a cover of Multifoil over 75 mm of existing (Where they put it) Rockwool. 100 mm Selotex. Then blocks topped off with recycled bricks polished and left self colour. Lower board paneling chosen.

Roof done in 2017 again Selotex on top of the rafters. Multifoil planned to be put in between. Rafters planned to be sanded and left self colour. Garage/spare lathe room roof replaced 150 mm Selotex on new beams. Sanded self colour.
The walls are next with 2 covers of Multifoil which should warm the house. Plus floor.
The outer wall on the landing is to be taken down and 2 layers put in and painted exposed bricks rebuilt. Window just replaced.
NO HEAT ON TONIGHT.

Watch Skilled Builder on You Tube as he covers heat pumps.
David and Lily.

[Jo]

It is interesting to go walking in the village after frost/snow to see whose roof remains "white" the longest (mine is one of them ). I suspect that blown in wall insulation will settle over time so it will be interesting to get my thermometer out and check the outside wall temperatures.

The biggest heat loss currently is the 1970's concrete block built extension, even with the wall insulation those walls can be a couple of degrees lower than both the older (1880s) or newer ( 2010) walls. I have considered external cladding but it strikes me as probably not very pretty. My current ploy is to close off those two rooms and only open them up when it is sunny and there is heat to "spare".


On the solar panels David: I assume you have a solar emersion controller to go with it. In the height of summer my 4KW array generates on average around 20KWh per day which easily provides me with hot water. Even this time of year the pathetic 1KWh is not lost and gets dumped in the water tank if I am not using any electric. There was promises of similar gadgets so you can use your excess solar power into your EV but I have not seen anything yet. I know my solar Emersion controller has a second power output that you can use to drive a resistive load but while I might use it to power a bar heater I am not sure I would want it feeding into an expensive EV charger...


I still need a long term solution to my house heating. While I am happy to chop wood, store and bring the stuff in I am not sure if I will still want to do it when I am in my late 80s or 90s. At the moment the only answer I can see is to plan to heat with straight electric heaters and tell myself I am only using the money I will have saved over the previous last half century.

Jo

[dscott]

With the rapid need for hand held Thermometers the price for small Thermal imaging cameras dropped so I got one and it showed many horrors walking down our road on a cold snow covered day last winter. Including parts of our house.

One super method is one that Thorn or Philips developed in that the room or exhibition hall can be cold but the special ruby heaters will heat up the LIVING BODIES walking round. Being in the development Prototyping side at Thorn Lighting we all borrowed the heater for a couple of nights. WOW. And it turned an unheated single glassed room into a super heated one. Cost unknown.
Tonight's research.

We spent the day battling Multifoil into the now cleared out difficult corner. 2 feet of rough inner walls with 2 layers.
The other wall round the corner which has no insulation as the camera told will have to be part of the CUNNING PLAN.
This is where we finish off the Utility room and turn it into a temporary kitchen next summer.
Then the current Kitchen comes out and the wall of windows and English Garden Doors gets rebuilt inside.

In our Workshop Extension we used Multifoil on all surfaces yes even the floor and this is warm.
At £85 a roll I have even made shutters for the windows while the last ones get replacements made.
Cunning plan would be to make a sort of big tent round a framework to sit in during the winter.
It is also light enough to put over the bed on very cold nights. We have used it in the car.

Yes. Todays sunshine has heated the hot water cylinder enough for 2 showers in the morning.

David and Lily.

[Jo]

Thanks for the heads up David: I've just looked at the price of the thermal cameras - under £50 each. Not sure if I can justify one at that price, I will just have to run my laser thermometer up and down the walls.

Jo

[jon38r80]

Looking at a Utube film today of someone checking the effectiveness of a water cooled exhaust for a boat generator, it seems there are Apps avilable for phones that filter the image from the phones camera. Apparently (perhaps not surprisingly) they are not as good as thermal imaging cameras sold for the purpose but they may be good enough for your purposes.

[chiptim]

Hi All,

I realise this thread is old but as nobody who owns a Heat Pump (HP) appears to have posted, I thought I’d share my experience having owned one for just over a year.

I have a 3 bed 80’s-built bungalow. Cavity insulation, reasonable loft insulation and double glazing all round. It’s about 108m^2.

The existing radiators and pipework were deemed sufficient to not require replacing, and its 10mm microbore to the rads. There are no thermostats on the rads, indeed the company stated not to fit them citing it better to leave all rads on full.

After the 1st year of running I calculated my SCOP (average efficiency for the whole year) as just under 3, and whilst it’s hard to calculate if this was more or less expensive that the oil heating system it replaced (as costs varied so much), my best estimate is that it was about the same, perhaps slightly less.

There’s much to like about my Air Source Heat Pump system:

• The house is always warm and comfortable;
• There’s plenty of hot water – We’ve never run out and its definitely hot enough!
• Hot and cold is now balanced at just over 3 bar so the showers are great compared to how they used to be;
• I was one of the lucky ones (if you view it that way) who succeeded in obtaining one of the Green Homes Grants, plus I get RHI payments every quarter for the next 7 years. Despite that the initial cost is high and the payback was supposedly about 5 years.

But in going the HP route it enabled me to get rid of the boiler from our utility room, allowing us to re-work the room into a much more useable space. It also got rid of the oil tank allowing me to build a great timber garden building without compromising its size and having to provide fire screening etc plus we don’t get the smell of oil drifting across the patio when we’re eating out. That that was never pleasant. I worry about climate change so like the fact that my HP is helping reduce our emissions.

So our reasons for going the HP route rather than simply getting a modern outside oil boiler were multiple.

The problems I’ve encountered:

Our bedroom was too warm for winter. We opened the window at night and I was ‘setting back’ the temperature down to 15 Degrees for night time causing the house not to be up to temperature on the cold mornings. This I’m told, loses some efficiency.

I hate the controller. Its touch screen is slow to respond and the menu is complicated. Worse still, when you make a change, it takes effect the next day. I have an app on my phone, but they’ve introduced a charge if you want the app to control the heating rather than just report its status. Well if they think I’m going to pay them monthly to control my own ‘top of the range’ expensive heating system, they can think again!

With hindsight, if electricity was still 15p/kWh, I would say I made the right choice. Looking ahead fills me with fear. What if the Government introduce electric rationing turning each area off for a while? That’s no good for a heat pump system that needs to tick over continuously. For the same reasons setting back loses efficiency, turning the power off for several hours would also lose efficiency. So the Governments rationing policy could actually cost me more.

Just to dispel any misunderstandings, an Air Source Heat Pump will work at -5 or even -10 degrees C, (not that I’ve had -10 here); they have a proven track record in Scandanavia for example. However what they don’t tell you is that an ASHP struggles most at a few degrees ABOVE freezing, especially on foggy/misty mornings that cause it to freeze up quickly so that it has to spend a significant amount of its time in the defrost cycle, which wastes energy losing efficiency. Sadly we get a lot of those conditions. It also becomes more noisy as it frosts up so the noise figures they provide are not applicable to all working modes/conditions/time.

What I’ve done this summer to keep the bedroom cooler without having to open the window at night is to upgrade the radiators in the living areas. You can buy unused or extremely good condition radiators second hand on various sites at a fraction of their new cost. This will allow me to lower the flow temperature making the HP run more efficiently whilst keeping the temperature the same in the living areas, but cooler in the bedrooms. A lower flow temperature will increase its efficiency and help reduce the freezing up in winter.

Fortunately I have a log burner, and I’m using my copper smithing skills to build a back boiler for it. This will provide hot water for an additional radiator in the kitchen and one down the hallway to put some heat down that end of the bungalow. Due to the forecast electricity prices I’ll only be able to afford to run my HP either for hot water only, or with the heating set to a low temperature, running the log burner to provide the remainder. It’s ironic that one of my reasons in splashing out on the HP was to cut my carbon emissions, and now I’ll be forced to burn wood and coal to keep warm due to the crisis, but needs must.

We can cope with the bedroom being cold. If it’s too cold, we’ll put another dog on the bed. 😊 Tim

[Jo]

Thanks Tim that is really useful. Could I suggest you invest (sorry more expenditure) in a solar array it will provide you with some free electricity to power your ASHP.

I used to have oil as my heating but the prices were erratic so I never knew what it would cost, then the boiler broke down and they deemed I needed a new one before I got round to it I found my oil tank had sprung a leak... By which time I was, like you, heating my house with my log burner and decided the oil system repair was uneconomical. Thankfully the government gave away the £150 in May which reminded me to buy in lots of logs at the point in the year when the prices were at their lowest.


Listening to this mornings 80% increase in prices of domestic energy costs I am greatly relieved that I invested in insulation, my solar array and my log burner as my monthly energy bill is going to be about £108 (currently £60). My neighbour who lives in the other half of the semi will have a £450 monthly bill with only his old age pension to fund it. I wait to see how long it takes him to admit that he should have taken my advice and buy some logs in when I did earlier in the year



Jo

[chiptim]

Hi Jo,

I'd love solar panels and battery storage but no funds left for either :-(
I need the most electricity in winter when the panels wouldn't produce much. What annoys me about solar is that the feed-in tariff isn't a percentage of the unit cost. It's disgraceful.
If I went only for battery storage, you only get 4 hours of cheap electricity during the night so I'd need a high power inverter and lots of batteries to store enough cheap electricity to be worth while.
What also annoys me is the pricing model of electricity in the UK whereby the cost of all electricity is set by the cost of the most expensive contributor to the demand at any time, i.e. GAS. Again, its disgraceful!
Also why are the RHI payments linked to inflation but not the cost of electricity? Again it seems so wrong!

Anyway I don't want to get off topic. I'm proud that my HP contributes to at least the equivalent of taking a car off the roads helping reduce my carbon emissions. We also sold one car and drive our remaining car far less mainly due to working from home. Of course I'm not counting what will come out my chimney this winter to keep warm :-( I guess there's some comfort in the fact that modern stoves produce much lower emissions than an open fire and that by burning wood the trees have at least absorbed lots of CO2 during their life, although releasing a lot quickly isn't helpful in these times. Anyway I'll stop there - I could go on and on...

I believe Heat Pumps are good, but not until the energy (electricity) crisis is resolved.

Tim

[Neale]

I'm starting to look at things like heat pumps as part of a fairly major renovation of my house. It's a mix of (probably) 19thC stone cottage plus 1980s cavity wall extension. It's half built into a hillside into the bargain. It brings up a whole series of issues, like how to insulate external walls, what about the roofs, is it worth digging up the ground floor to install insulation and possibly underfloor heating to go with it? We are currently on holiday in the Outer Hebrides, in a modern well-insulated cottage with ASHP underfloor heating. No problem with warmth, but with the windows closed the atmosphere becomes rather stuffy and unpleasant - so do we also need MVHR? That's mechanical ventilation with heat recovery - I've recently learnt! And apparently the way to go for new builds, if the budget stretches to it. Draw air from rooms like bathrooms and kitchens, pass it through a heat exchanger, and feed the warmed fresh air into living areas. There's a whole bunch of things to think about but I'm also unsure about who to trust for independent advice - our neighbour recently built a new house, timber-framed and insulated to a high standard, with underfloor GSHP heating. The original GSHP installer went bust halfway through the build and the guy our neighbour eventually found to finish that part of the job seems to have been a bit of a cowboy. I get the feeling that these new technologies are a bit too new for otherwise competent traditional builders.

Anyway, very interested to read other people's experiences - and that there is still a role for a log-burner! We get a fair bit of fallen timber in our garden...

[terryc]

Looking on prime location a few weeks back as thinking of downsizing. There was a bungalow complete with heat pump, two wood pellet burners and the rest of the green nonsense. On the energy certificate it had details of the last electric/gas bill. It was double my own bill which is for a very none energy efficient grade 2 listed house. So go figure. There is a very old saying. You don’t get anything for nothing. The whole green nonsense is based on getting something for nothing. It just doesn’t work.

[abby]

You mean like crypto currency ?

[Jo]

Another update on running costs:

Cost in replacing the heat exchanger fans at least 4 times over the 20 years life time of the heat pump.

Jo

[Neale]

That's for air source, presumably?

[Jo]

Yes sorry. Air Source ones have fans. Ground source have those lovely big heat exchange tanks you have to find somewhere for.

Jo