Saving the Planet … or is it ?

What happened to the solar panels that just heated water ? They seem to have died out

Roy

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Me too, Mick … but my limited exploration of the subject leads me to believe that if I had a stream conveniently running through my property, a ‘water-source’ heat pump would be ideal … but otherwise, the cost/benefit analysis doesn’t seem to work. [yet]

MichaelG

If I had a stream running through my house , I'd go hydro-electric , problem solved.

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So now I suppose we need to define ‘stream’

MichaelG.

A water source heat pump would be a big improvement indeed, tempered a little by the escalated home/contents insurance premiums from having a stream running through your property.

A place that always stuck in my mind as being the perfect location to extract heat from was a house I visited one frosty November just south of Newcastle, Staffs at about 7:30 in the evening. As I walked around the back of the property I felt warmth on my face and there were ripe figs and a grape vine with bunches of grapes. No frost or any cold at all. The owner said there was a micro climate caused by a stream that ran down the side of the property and along the back. The property was effectively enclosed on three sides by a disused railway embankment, a steep wooded bank and a bund to reduce noise from the M6. Up to his house the stream was deeply culverted and emerged on his land.

the best thing to do is to take early retirement take ur tools/machines and go live in the sun.....

leave that wet cold and downtroden place to those at the top and then find out who's gonna pay for these mad hatter schemes......

I say remove the VAT on anything like solar heating and other improvement and leave the Gas boilers alone......

The way I heard it from a borehole engineer, u need to be down at least 300m to make any real difference to heating and more if u can......

what HP poump will u need to get the hot water back up to the house from that kinda depth....?

then as all land under ur house is owned by Queeny will there be extra tax to pay her.....?

spose she needs the extra to support all those hangers on.....

the like's of Boris and I'm a supporter should be told to go stuff his self and all his mates who will make a fortune from the lowley masses.....

the Uk can make a start but China and co needs to also help....

the Geotherm idea was hatched up in the pub after 10 pints of foaming brain neutralizer.....

The Brogan runs through my property..officially labelled a river on OS maps, I can step across it in summer and possible clear it in a running jump in winter when (to be fair) it can rage. At a distance of 200+yds from the house any heating source becomes uneconomic and sadly fall is more use than flow when considering micro-hydro. It'd have to be an undershot wheel and my calcs on cost to build and cable runs for the likely generation just doesn't compute. There is a deep drainage ditch 130yds to the side of my property that has the remains of some ancient power mechanism implying that historically water flow was greater back then.

pgk

Roy, you can still get them but they are not really cost-effective.

We built our house in 2008 and I installed them when the roof was put on. Buying the panels at trade prices and installing them myself still cost around £1250. We probably get about £50 worth of free energy a year giving us a payback of 25 years. Paying to have them retrofitted to an existing house would cost a minimum today of £4000 - 80 years payback!!

Even so it is great to turn off the boiler in March/April and not put it on till October/November and still have a supply of hot water - it does get a bit lukewarm in prolonged periods of overcast weather though.

Steve

Ground source heat pumps are much better than air-source but are so much more expensive to buy and install.

Air-source does work in dry climates but my research indicates that they do not perform very well in damp environments, like the majority of the UK, as their COP drops off due to ice build up and the need to constantly de-ice them by reversing the cycle.

I would like to do my bit and install one but I fear I would still end up using the same amount of energy to heat my house as I am doing now.

Steve

I became interested in heat pumps after read ing a book in the early 60's in the technical college library called "Domestic heat pumps" by John F Sumner. Of course at the time nothing was know about them but as the years have chugged on they have become more to the fore and I always thought that some day I would experience a heat pump.

Our house has underfloor heating with an oil boiler but eventually I got fed up with oil cost so rejigged the heating and installed a 7kw output heat air source pump which worked reasonable well but didnt have enough grunt. Changed this for a 22kw output ASHP (Ebay) and the oil boiler has not been fired up for 6 years now so some sort of a success but I'm sure I'll hear more!

Not for everyone I'm sure as can be noisy depending on location and gives running cost somewhere near gas. Major disadvantage is it cannot reach the same temps as a normal boiler so not an instant swap for a gas boiler in most cases.

Peter

Installing a heat pump in an existing property is where it gets costly. Really, radiators are not so good and underfloor heating is better for the lower water temperature. Older houses also don't have anywhere near the insulation to be effective. The best outcome would be a new build that's designed to be thermally efficient to begin with, but that's not going to solve anything for owners of existing properties.

Peter did you change your hot water tank when you installed the bigger ASHP?

Steve

Edited By Steve Skelton 1 on 24/10/2021 14:47:56

Yes I changed the cyl Steve. Perhaps better add that we are a new build from 2000 but not terribly good on insulation, wanted better but building regs awkward/dodnt understand at the time. Also have heat recovery ventilation which is excellent.

The original system used a large cyl which incorporated a thermal store and heat exchanger for the underfloor but was designed to run UF at 65/70C. Not very good for effienciey but nice and hot as was the house, and used lots of oil. Cyl was showing signs of leaks at the time of the small HP experiment.

Now run UF from a heat exchanger direct from HP, output from heat exchanger goes to a dedicated thermal store then pumped back to the HP. This prevents the HP cycling. When the thermal store is up to temp(48C) HP is off and another pump circulates the contents of the thermal store to the UF heat exchanger. At 42C HP it changes over and HP on again and the cycle repeates. Could have just circulated HP to thermal store but this way UF get the benefit of quicker temp rise.

I have motorised ball valves to change HP over to heat the cyl as needed, can be automatic but cyl has seperate thermostats to control HP. As most of the time a lot of hot water is not needed run cyl at 35C and have undersink instant elec heaters to boost to 50C which also works for the shower.

The UF piping is plastic/rubber as was designed for us, could be better on heat transfer especially through carpets. If I was doing it again would use rads and UF but circulate to rads then onto UF on return from rads. Did this on my sons house(gas fired) and it gives the best of both worlds, UF heating very nice and cosy!

Peter

My granddaughter lives in a cottage attached to a large farmhouse, both buildings are fed heat from a ground source heat pump, plenty of land in which to locate it. The radiators in the cottage are never more than lukewarm and definitely are insufficient to heat the cottage during winter so they have a large inglenook fireplace with a woodburner which at least keeps their lounge warm. We have solar PV panels and batteries at our house and I researched a heat pump installation, ours is only a moderate size house but we would need a fairly large capacity heat pump and even though our house has good insulation we would struggle to achieve a reasonable heat. The installation costs would be considerable and for less benefit that we currently enjoy with our gas boiler, I think the establishment will have a hard job selling heat pumps instead of gas boilers, how long till this pipe dream crashes and burns and we continue with gas boilers. Dave W

Steve, Just re-read your post about damp climate. Our does freeze up but still works when its a block of ice until it does a defrost cycle which looks pretty impressive but as you say the COP is pretty poor at that time. I've heard of problems with ground source HP due them freezing the ground giving poor themal transfer especially if its dry or sandy ground but not got direct experience of them.

Only advantage I can really see from my experiment is that they do work and the electricity can come from any source green or otherwise but they are definatly not a direct replacement for a boiler on cost and output temperature as most posters have outlined.

Peter

Heat Pumps may be a pipe dream, but gas boilers are becoming a nightmare! Since January the wholesale price of gas has quadrupled, bankrupting no less than 12 UK energy companies whose Fixed Tariff contracts prevented them from passing the increase on to customers. So far variable tariff customers have been protected by the government price cap, but this will be increased soon.

Wholesale prices have risen before winter demand kicks in and is a worldwide phenomenon. In future we can expect to pay more for gas. People will dump gas boilers when they become more expensive than the alternatives.

I wonder what we'll be paying for gas this time next year? Nothing changes minds like a big bill!

Dave

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Hence my hypothetical interest in a ‘water-source’

MichaelG.

Yes indeed and the first commercial installation to heat a large building used water from the river Wensum in Norwich as a heat source. This was designed and built by John Sumner and started opearation in Oct 1945 but only lasted for a couple of years due to corrosion of the plant and nationalisation of the electricity industry.

Peter

Hi Peter,

Thanks for the information. Likewise, we are also a new build, from 2008, but with lots of insulation – 140 mm in walls, 150mm in floors and 200+ in ceilings. We have a lot of windows (D/G) so that is the main heat loss. We also have whole-house ventilation with heat recovery which as you say is excellent – never seen any condensation on windows in any room except bath/shower rooms and then for only a short time.

We have a 500L thermal store with wet solar panels and a wood burner with a back boiler feeding the store. Main heating is an LPG boiler through a coil in the T/S – this is the biggest restriction we have in using a heat pump, the contact surface in the coils is only 1.2m2 which limits the size of heat pump I can strap onto it – probably to about 5kW. Pipework to this coil is 22mm and is about 28m from the boiler (and proposed ASHP site). I do not really want to change the store at this stage.

Feeding new ASHP feed pipework to the store would be very difficult due to the UFH in all rooms and therefore lifting floors is not an option so I was looking to use the same pipework for the ASHP as the boiler uses. I would do this with interlocked motorised valves to isolate each system and use a control system to send appropriate signals to the LPG boiler, ASHP and valves.

Our house thermal loss is between 225 and 275 W/K so in theory, a 5kW pump should be adequate for all but the coldest of weather. I would like to keep the LPG boiler as it can be run in a combi mode for hot water if the store temperature is not high enough ( ie when using an ASHP). We like to run the wood burner in the evening when we are in the house so again this helps with heating the store.

Our annual gas heating bills on bottled LPG are less than £500/yr although that does not take into account the wood that we burn which is free (we have a lot of trees).

I am very interested in the fact that you still get a high efficiency from the ASHP when it turns into a block of ice – I was under the impression that ice acted as a good insulator to prevent heat transfer. It has been this one issue that has prevented me from experimenting with an ASHP.

Where in the country are you? We are in the South West.

Thanks, Steve

Hi Steve,

I did very similar to what you are suggesting (see pic) so I retained the use of the original boiler if I wanted it, in practice never used it for ages. Sometime think it would be useful to do a costing of each system but l'd rather do something more interesting....

Think our original themal store was around 300l but replaced this with a 90l thermal store and presurised SS cyl which I think is 150l. I hoped the SS cyl would be less prone to leak /corrode and seems fine up to now.

Not sure what the COP is when its in block of ice mode but the parameters for a defrost can be set, think I've got mine set for the min of 1/2hr continous running also taking into account the condensor temp.

Being a "budget" ASHP its suffered from spade connectrors overheating/burning, replaced with eyelets onto the existing studs and capacitors failing. I've replaced the start and run caps with decent run polyester ones. The two schroll compressors are Toshiba. It also has 2 fans pulling air through the condensor. Earlier this year I noticed one fan seemed slightly slower than the other so removed panels etc. When I put my Smiths tacho onto the top fan discovered it was doing 500rpm and when pushed the tacho onto the bottom fan it slowed and stopped-mmm! More digging revealed that the fans are 960rpm and the caps had gone from 4uf to 1.5uf. Changed these and its producing a howling gale once again which should improve the low temp performance and perhaps help keep the condensor freeer from ice. Not sure how long its been running at the lower effiency though.

I still have the smaller ASHP sitting in the garage Steve but unfortunatly I'm in Staffordshire else you could have had look at it all and even borowed the smaller ASHP to try/play.

Peter