How Boz

[Thingybob]

So we now have till 2035 to phase out gas boilers thought it was 2025 in new builds anyway where are we going to fit ground heat pumps in terraced houses with a back yard of 20ft x20 ft and on flats , Near me the counsil /developers are building blocks of flats on any spare sites and demolishing old buildings to erect multi stories and i have not seen any ground pumps going in ( Im getting woried as there is an old phone box at the end of the road prime ground for a three story dweling ) But seriously where are we going to lay under ground piping when you cant see any open ground round buildings . Come on Boz tell us the story ( think i might know which minister "retired" he may put in charge of that dept)

 

[Phil Pascoe]

Mains gas will have bypassed us, we've never had it. Interestingly, the Vaillant unit shown in the BBC news reports is apparently a hybrid heat exchange/gas unit, almost an admission that they don't work all the time. I've read that the heat exchangers work at their very best when the weather is hot and you don't need the heat and at their worst when it's very cold. At building density around here people will need pipework in their window boxes.

 

[Thingybob]

So what we need is genetic modification of humans so they are warm in winter and cool in summer must be a cheeper alternative and certain people can have thier warm period tweeked so as to start in late July and swop over in late May (no gender reference )

 

[Spectric]

I think Borris and co are hedging their bets that by the time gas boilers are phased out global warming will be good enough for us not to require much heating in our homes. If they were serious about the enviroment then they would not be butchering ancient woodlands, looking at a new coal mine and would have already changed the building regs to ensure the real homes of the future are built now and not the sprawling mess of poor quality hutches that will be around for the next fifty years, but you don't want to upset the wealthy property tycoons who help fund your existance do you. The current british climate is not well suited to these air source heat pumps but again maybe as we get warmer they will suffice, big problem is that it could go the other way and we end up with a climate like Cananda, we are on the same latitude after all.

 

[doctor Bob]

I have a GSHP, get a grant every quarter. Basically paid for the system over 7 years.
They can be bore holes don't need to have massive garden.
Most will be replaced by Air source surely.

 

[gcusick]

We too have had a ground-source heat pump for the last (nearly) 9 years, since building our house. Gas was not an option, as there’s no mains gas here. The house is ~270m^2, well-insulated, with underfloor heat throughout. We have 3 boreholes, in an area 5m x 5m, totalling about 210m of hole. The heatpump comfortably maintains a uniform 22C everywhere, in addition to providing domestic hot water.

Retro-fitting a heatpump into an existing house would be harder, but, while researching our installation, we did see a couple of entirely successful GSHP retrofits, one using horizontal collectors under (essentially) a paddock, the other in a refurbished ‘30s bungalow, using boreholes. So it can be done effectively and reasonably economically.

The bit that’s missing from the government’s “strategy” is the essential first step: insulation. One of the first pieces of advice we had when designing our heating system was “The best way to heat your house is to insulate it.” Absolutely. But that’s not as glamorous as giving grants for questionable heatpump retrofits. Yet another example of slack, piecemeal thinking.

 

[nickds1]

Ditto. Have had a GSHP since 2005 - one of the earliest domestic ones in UK - did it as part of a self-build. Not missed a beat since install and commission.

Ours is three phase - it's the primary heat source - does all hot water, heating etc.

 

[baldkev]

I think the government probably thought that by the time 2025 rolls around someone would have come up with a better solution.... maybe now by 2035 there'll be a better solution

So how much is a ground source heat pump system for an average house? We are hopefully doing an extension next year and will have to replace our boiler.... which will be about a grand, plus flue kit, plus fitting.... and ongoing ( and rising ) gas costs

 

[Spectric]

I think very high levels of insulation are needed and this will make the walls thicker, not good for property developers as it reduces the number they can squeeze into a space and underfloor heating rather than traditional rads as it runs at lower temperatures and delivers heat from the floor up which helps provide more uniform temperatures.

 

[nickds1]

Depends what you mean by "an average house". We're 7 double bedrooms and about 4,500sq ft. Self build in 2005 around the core of a Victorian oast.

GSHPs are slightly more efficient than ASHPs and have less moving parts - generally they need less maintenance and are largely set-and-forget. GSHPs get their energy from either horizontal "slinky" coils or very expensive deep vertical bore holes. If you have 3ph, use it as the pumps and compressors are just that bit more efficient again than 1ph - incremental gains and all that stuff...

ASHPs obviously don't need any underground pipework and can be installed in restricted space or where ground conditions don't allow sub-surface work.

Both GSHPs and ASHPs count as solar. Both systems are best at producing heat around 40-50C, so ideal for underfloor and general hot water (you don't have to add cold to mix it down - it's just right straight out of the tap). Once a week they have a sterilisation run where the hot water is raised to about 60C for an hour or two to kill any lurking legionella or similar - the normal operating temperature is too low to stop bugs multiplying.

Standard emitters, i.e. radiators, need to be oversized wrt. those used for gas CH as the temperature is significantly lower. Folk complain a lot about having to replace older radiators with newer ones, but the replacements are often smaller than the old gas CH ones as the new ones are far more efficient designs.

Heat pumps also produce slow, gentle, continuous heat rather than the full-on anger of a gas CH system, thus they perform far far better in well-insulated and non-draughty buildings. They tend to run continuously and do their own thing - not something that you have on for an hour in the morning and an hour or so at night.

Thus you have buffer tanks for hot water and UFH - in our case the system produces up to 300ltrs of hot water an hour, regardless of the time and outside weather.

We have 3x55mtr trenches, each 1 mtr deep and 1 wide - each trench contains 200mtrs of pipework - think a 200mtr long 1mtr diameter coil of alkathene pipe just pushed sideways in each trench. Each trench is connected in parallel, so the exterior loop is 200mtrs long but contains 600mtrs of pipework.

 

[doctor Bob]

Depends what you mean by "an average house". We're 7 double bedrooms and about 4,500sq ft. Self build in 2005 around the core of a Victorian past.

GSHPs are slightly more efficient than ASHPs and have less moving parts - generally they need less maintenance and are largely set-and-forget. GSHPs get their energy from either horizontal "slinky" coils or very expensive deep vertical bore holes.

ASHPs obviously don't need any underground pipework and can be installed in restricted spaces.

Both GSHPs and ASHPs count as solar. Both systems are best at producing heat around 40-50C, so ideal for underfloor and general hot water (you don't have to add cold to mix it down - it's just right straight out of the tap).

Standard emitters, i.e. radiators, need to be oversized wrt. those used for gas CH as the temperature is significantly lower.

Heat pumps also produce slow, gentle, continuous heat rather than the full-on anger of a gas CH system, thus they perform far far better in well-insulated and non-draughty buildings. They tend to run continuously and do their own thing - not something that you have on for an hour in the morning and an hour or so at night.

Thus you have buffer tanks for hot water and UFH - in our case the system produces up to 300ltrs of hot water an hour, regardless of the time and outside weather.

We have 3x55mtr trenches, each 1 mtr deep and 1 wide - each trench contains 200mtrs of pipework - think a 200mtr long 1mtr diameter coil of alkathene pipe just pushed sideways in each trench. Each trench is connected in parallel, so the exterior loop is 200mtrs long but contains 600mtrs of pipework.

I have a very similar set up installed in my new build in 2016, approx 600m of pipework in 6 trenches. 540L of hot water. Underfloor heating. I love it, we generally maintain the house at 23deg, can push it to 25deg but thats the limit. Also have an 8KW log burner boosting heat in lounge. If I hadn't been able to get grant, I would have gone a different route due initial expense.

 

[baldkev]

Depends what you mean by "an average house". We're 7 double bedrooms and about 4,500sq ft.

I think an average house would be 3 bed, not a mansion
That said, we are moving in with you! I can rent our house out and you wont even notice we are there

 

[Fitzroy]

It’s the historic housing stock that’s difficult to effectively insulate that I think is the elephant in the room.

Here in Aberdeen many of the city homes are granite built, with thick solid stone walls. Internally you have lath and plaster with a ventilated air gap behind. This is designed to manage the issue of damp due to penetrating wind blown rain. The granite is not a lot more than a structural rain screen!

I’ve done lots of research but there are no tried and tested solutions except to rip out all the internal lath and plaster and rebuild with insulated walls. Many of the houses are large so have the space, but the cost would be abhorrent.
Fitz.

 

[Terry - Somerset]

GSHP solution seems the most reliable, the most costly, and most complex to install. Although efficient it still requires an external electricity supply.

ASHP is cheaper and simpler to install, but less efficient. For a given amount of heat it requires more external power. It is also somwhat sensitive to ambient temperatures.

Conventional proven split aircon/heating units could provide space heating with a high level of efficiency. Also needs external power and (AIUI) cannot provide hot water.

The external energy needed can come from (a) the grid, or (b) a mix of grid and PV, or (c) PV + battery storage. In theory all domestic power could be provided by PV + battery.

Solar water heating - fairly simple, easy to retrofit. Sensitive to day/night and cloud cover, but hot water storage is easy. Hot water storage could in part substitute for batteries.

Decent insulation and energy controls are required irrespective of whether conventional or green energy sources are used. - so no real change there.

All solutions require external power and depends on the technology used for hot water and space heating. Cooking and lighting need simple KW. There is a trade off between domestic PV (+ battery) capacity vs grid supplies to deliver both total and peak demands.

The medium term strategy is for substantially all grid supplies to be green or nuclear. If grid is more efficient then domestic energy provision may be marginalised.

What does all this mean - we need a far more intelligent strategic approach to domestic energy and grid generation. It is not a simplistic - "fit a heat pump". There are trade offs and options depending on circumstances - location, age/type of property, finance, efficiency etc.

 

[Thingybob]

Ok all this is ok if (1) you are still quite young and can afford to pay off instalation over many years (2) you are prepared to put up with upevil of the mess all this is going to cause (3) insurance to cover any failures along the years. Not every one can afford to self build which negates the inital upevil as its a mess while building Im talking about retrofit instalations for those that have retired

 

[Just4Fun]

GSHPs get their energy from either horizontal "slinky" coils or very expensive deep vertical bore holes.

Another option is straight horizontal pipes, which is what we have. Slinky pipes are a good solution if you have a limited area in which to place the pipes. We did not have that limitation so straight pipes were a better bet. Yes, it needed a longer trench (we have 800m of pipe) which can add to the cost of digging, but you don't need such a wide trench which offsets that a bit.

Standard emitters, i.e. radiators, need to be oversized wrt. those used for gas CH as the temperature is significantly lower.

We were lucky in that our existing (oil-fired) central heating already ran at a lower temperature - maximum around 55C - so we did not need to change any radiators.

Heat pumps also produce slow, gentle, continuous heat rather than the full-on anger of a gas CH system, thus they perform far far better in well-insulated and non-draughty buildings. They tend to run continuously and do their own thing - not something that you have on for an hour in the morning and an hour or so at night.

This can be a tricky one to get your head around if you are used to the approach typical in the UK of running the heating for only part of the day. That can actually cost more with a heat pump because when it comes on after being off for a few hours the back-up resistive heating (basically a big immersion heater) can kick in and that is more expensive to run. Add in low-rate night time electricity into the mix and it is not always obvious how best to set the controls.

I’ve done lots of research but there are no tried and tested solutions except to rip out all the internal lath and plaster and rebuild with insulated walls.

Our house is a totally different construction. Originally just solid log walls it later had wooden ship-lap style outer covering and internal batten and fibreboard insulation added. I have had the same problem though: I cannot find reliable & understandable information about how to improve the wall insulation. There are lots of horror stories about old log buildings being ruined by modern insulation causing problems with damp & mould

GSHP solution seems the most reliable, the most costly, and most complex to install.

Generally reliable yes, although ours has not been entirely trouble-free. Costly to install (but not to run). Complex to install? Not complex ecactly - there is nothing complex about digging a trench and putting a pipe in it. Maybe involved would be a better word.

ASHP is cheaper and simpler to install, but less efficient. For a given amount of heat it requires more external power. It is also somwhat sensitive to ambient temperatures.

I do wonder if this might vary according to the time of year. In winter, when ground temperature is significantly higher than ambient I expect GSHP is far better, but what about in spring and autumn when ambient temperature is above ground temperature? Is the higher-temperature heat source enough to offset any lower efficiency of ASHP?

Solar water heating - fairly simple, easy to retrofit.

I fitted evacuated tubes and they work well. Most of the time we put their output into the heating system though, not to hot water. That is a better use for us. Also we have a problem in that the only real location suitable for the tubes is a long way from the hot water tanks so there is heat loss along the way.

It is not a simplistic - "fit a heat pump".

Effectively that is what we did. We fitted a heat pump and connected it into the existing heating system. We didn't change anything else; we didn't even remove the old oil burner which still exists "as a backup".

Ok all this is ok if (1) you are still quite young and can afford to pay off instalation over many years

That is a very good point. Older people and/or the less well off can really be disadvantaged. If heat pumps were the best solution for all then everyone would fit them anyway and no mandate would be needed.

 

[highwood122]

We too have had a ground-source heat pump for the last (nearly) 9 years, since building our house. Gas was not an option, as there’s no mains gas here. The house is ~270m^2, well-insulated, with underfloor heat throughout. We have 3 boreholes, in an area 5m x 5m, totalling about 210m of hole. The heatpump comfortably maintains a uniform 22C everywhere, in addition to providing domestic hot water.

Retro-fitting a heatpump into an existing house would be harder, but, while researching our installation, we did see a couple of entirely successful GSHP retrofits, one using horizontal collectors under (essentially) a paddock, the other in a refurbished ‘30s bungalow, using boreholes. So it can be done effectively and reasonably economically.

The bit that’s missing from the government’s “strategy” is the essential first step: insulation. One of the first pieces of advice we had when designing our heating system was “The best way to heat your house is to insulate it.” Absolutely. But that’s not as glamorous as giving grants for questionable heatpump retrofits. Yet another example of slack, piecemeal thinking.

 

[highwood122]

i assume you cook with electricity, so what are your annual bills

 

[Just4Fun]

i assume you cook with electricity, so what are your annual bills

Who are you asking?

 

[Rustic Mike]

So we now have till 2035 to phase out gas boilers thought it was 2025 in new builds anyway where are we going to fit ground heat pumps in terraced houses with a back yard of 20ft x20 ft and on flats , Near me the counsil /developers are building blocks of flats on any spare sites and demolishing old buildings to erect multi stories and i have not seen any ground pumps going in ( Im getting woried as there is an old phone box at the end of the road prime ground for a three story dweling ) But seriously where are we going to lay under ground piping when you cant see any open ground round buildings . Come on Boz tell us the story ( think i might know which minister "retired" he may put in charge of that dept)

My mum bought her council flat, and didn’t have to have an heat pump fitted, the flat above did, and they fitted it on a bracket type girder on the gable end outside, they ende up having loads of trouble with it, and when there was a cold spell it sounded like a jumbo jet, and my mum and dad had some bad nights sleeping because of it, the other problem came every time they had to fix it which was about every six weeks, and because of health and safety had to be scaffolded every time, it ended up costing that much they were put back on gas boilers again, nobody thought it was any good at all the houses were always cold and it cost more, but now everyone is warm again, and they all lived happily ever after.