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.