Yes, you should see the hoops my neighbour has had to jump through doing a garage to bedroom conversion for a customer.
Air source Heat Pumps any good?
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Agent_zed
Established Member
They are all still heated with combi boilers with no provision to change to ASHPs even if they wanted to as no tank space.
The only house with solar panels, on the 350 house new estate next to me, was retrofitted by the owner.
Yet another estate 10miles away from me every house had them fitted when built 10 years ago? I bet those people are glad they have them.
If you fit 350 solar systems at the point of build they will be a fraction of the price compared to retrofitting.
Same with the local lidl store built last year. No solar panels, yet huge flat roof perfect for a large array that would run the fridges/freezers/ovens/servers/tills/lights that are on constantly.
I live in a rural town but you drive into the estate and you could be in a city, just a sea of tarmac and bricks. Give it few years and the few small grass front gardens will be paved over for extra parking.
And yet no extra school, dentist or doctor provision for our town. There is more to houses that just the buildings.
The social housing estates being built here all have solar panels.
No schools, doctors, dentists, sewers, reservoirs ...
AJB Temple
Finely figured
Well agent zed. I agree that provision for local services is usually woeful, but that is the responsibility of local authorities to insist developers fund it and to ensure it is built. Local authority councillors in our area are obsessed with vanity projects such as white elephant community halls.
The solar panels argument is complex. Certainly on the estates being built near us, solar panels are incorporated. I recently spent a day at a mixed use (offices, retail, housing, medical) estate quite near us. I was super impressed at the build quality, which included very sizeable arrays of solar panels, semi transparent, to create large canopies and porches. The designs used adjacent "rewilding" to install ground source heat pumps, and they also avoided hard paving with permeable gravel filled parking block grid areas and paths. Numerous electric vehicle chargers including about 10 Tesla superchargers. Water recovery systems in evidence. Sustainable materials (heavy duty softwood framing and glulam).
The issue developers face is that the houses they build have to sell. The more you add in solar etc, the higher the price. This affects social housing disproportionately, though I am aware of two developments in progress nearby that do include solar panels. In both cases these are installed on communal use designated car ports, rather than dwelling roofs. This may well be for maintenance reasons.
It's not perfect, and sewerage facilities continue to be a problem for many developments (overloaded plants in third party control), but overall it is, in my observation at least, moving in the right direction. It's taken too long though.
The solar panels argument is complex. Certainly on the estates being built near us, solar panels are incorporated. I recently spent a day at a mixed use (offices, retail, housing, medical) estate quite near us. I was super impressed at the build quality, which included very sizeable arrays of solar panels, semi transparent, to create large canopies and porches. The designs used adjacent "rewilding" to install ground source heat pumps, and they also avoided hard paving with permeable gravel filled parking block grid areas and paths. Numerous electric vehicle chargers including about 10 Tesla superchargers. Water recovery systems in evidence. Sustainable materials (heavy duty softwood framing and glulam).
The issue developers face is that the houses they build have to sell. The more you add in solar etc, the higher the price. This affects social housing disproportionately, though I am aware of two developments in progress nearby that do include solar panels. In both cases these are installed on communal use designated car ports, rather than dwelling roofs. This may well be for maintenance reasons.
It's not perfect, and sewerage facilities continue to be a problem for many developments (overloaded plants in third party control), but overall it is, in my observation at least, moving in the right direction. It's taken too long though.
Misterdog
Established Member
Gas only does that when in condensing mode. Common fallacy.
The marketing people push the '90 %' figure to sell product.
When not in condensing mode they are only C 70% IIRC.
My Ideal boiler tells me that it is in condensing mode for only 57% of it's burn time, though obviously this varies dependent on each use case.
When we first installed our GSHP we were regularly blowing fuses on one of the phases in its 3-phase supply and the wiring feeding power into the fuse board was getting hot because it was overloaded. It turned out that the supply to the house was actually a lesser standard than all the records showed, so at some time in the past someone had pulled a fast one and saved some money on the cable that was installed. We had to have new cabling to the house to fix the problem. It had not occurred to me before now that the blown fuses were caused by a power surge at GSHP start up, but it would certainly fit in with our experience.
John Brown
Freeloading Social media influenza
I think you'll find that this is a feature of all electric motors. I was of the impression that a lot of motorised appliances, such as fridges, washing machines etc. were being built with inverter drives these days, one of the reasons that new RCBOs are being introduced, which I would have thought, with my knowledge born of studying "The Boy Electrician" could alleviate the startup surge. Maybe the motors in ASHPs are much beefier than those in white goods, and inverter drives would be costly.
Used to be the case but not any more - most have inverter drives that spin up the compressors slowly and no spikes in current draw although they do recommend using C curve RCBOs due to the “shape” of the ramp up
Most ASHP are rebadged compressor units anyway - see a lot of Mitsubishi and Toshiba inverter drives in the lower end units too. Control systems are where the innovation happens by manufacturer
Jaco
Established Member
My 2 bits from way down South ...........
Our building regs in place when our house was built was either a solar hot water panel connected to the geyser (required a circulating pump) or a heat pump.
The pipes in the roof are insulated as well as the geyser has a blanket.
We opted for the heat pump which after nearly 9 years runs well and heats up the water in the geyser.
The geyser is 200 litre.
The heat pump is "I Heat Metraclark"
When we had solar electric installed I also had a new change over switch on the DB board installed - it is either 'geyser' drawing power of 3kw or pump.
The pump starts off at 1.5kw and then runs on 1kw.
Both are connected to our solar system, we are off the grid.
The heat pump comes on at 14:00 and runs for about 30 minutes, 45 in winter.
The next morning shower water is still extremely hot.
The pump and fan motor are not noisy.
Our building regs in place when our house was built was either a solar hot water panel connected to the geyser (required a circulating pump) or a heat pump.
The pipes in the roof are insulated as well as the geyser has a blanket.
We opted for the heat pump which after nearly 9 years runs well and heats up the water in the geyser.
The geyser is 200 litre.
The heat pump is "I Heat Metraclark"
When we had solar electric installed I also had a new change over switch on the DB board installed - it is either 'geyser' drawing power of 3kw or pump.
The pump starts off at 1.5kw and then runs on 1kw.
Both are connected to our solar system, we are off the grid.
The heat pump comes on at 14:00 and runs for about 30 minutes, 45 in winter.
The next morning shower water is still extremely hot.
The pump and fan motor are not noisy.
NormanB
Established Member
It seldom gets mention because the starting current of an induction motor is always higher than the running current. It always has been.
However, moving on - once the heat pump is running (and presumably that’s because the homeowner wants to heat their home) if the heat pump has been integrated correctly into the home and has the correct controls then it is not an off device and will modulate according to demand, yes this will affect running current and draw from the grid, but nothing like the surge experienced on compressor start.
When talking about ASHP startup current, I don't know where posters get their "facts" from. Regardles of pros or cons. I installed Misubishi Ecodan units 7Kw ten years ago. They were quiet and I never noticed any lights flickering when they cut in. The current Ecodan models quote a start up current of 5 Amps from a normal domestic supply. I am currently building a new house (for daughter) and the insulation requirements are massive. To achieve the energy performance level required an ASHP will be fitted (box ticking). My daughter on serving a customer with a well known companies logo (Heat pumps etc.), quized him. His experience (as the companies field service engineer) is that most of the problems with ashp are their installation, he stated that heat pumps consume huge volumes of air and need to be in the open not shielded away. Advice that is duly noticed and has led to us relocating the pump position when it is installed to the West face rather than the intended East side. East would have been a much less obtrusive site.
John Brown
Freeloading Social media influenza
Excuse my ignorance, but how does 7kw equate to 5 amps?
Surely 7kw can't be the equivalent heat output, as our gas boiler is 28kw.
Put simply, it doesn't. We are talking about the start up power consumption of the pump motor which is pretty much a fan. Plenty of information on the web about the technology and how it keeps the startup current low. This was the point I was answering to the post by mc281. Read this brochure and look on the web for deeper explanations.
Whether we like it or not Government(s) are trying to remove oil & gas boilers and push us the Heat Pump way. If you are really bored you can consult Bldg.Regs on The Energy Performance Certificate, which has become so complicated that you need to pay to initially have a projected rating followed by a final check to get your (required) Energy Performance Cetificate at completion of build.
Whether we like it or not Government(s) are trying to remove oil & gas boilers and push us the Heat Pump way. If you are really bored you can consult Bldg.Regs on The Energy Performance Certificate, which has become so complicated that you need to pay to initially have a projected rating followed by a final check to get your (required) Energy Performance Cetificate at completion of build.
AJPTemple, You mention local authority funding. The Civil Infrastructure levy (CIL) is designed for that. All developments have to pay this up front (some v. small developments excused), these sums can be huge. What the local authority does with this money is a mystery. Our area (like most in the UK) has seen massive housing developments but there are no new facilities.
RogerS
Established Member
Lose it on crypto-currency or other dodgy financial instruments ?, Like Thurrock, perhapd ?
John on the Wirral
Established Member
When we were kids we used to put our finger over the outlet end of bike pump and it got hot when we operated the pump - that is a air-sourced heat pump. It is a very simple principle. If you force air at the ambient outside temperature through a fine venturi it will get hotter. But how much hotter? If the outside ambient temperature is is not too far removed from what you hope to get out then you will have warm energy but I doubt whether it would be hot enough for a bath say. What if the outside ambient temperature is minus 10? The electric pump would need to work it's socks off 24/7 to get the water something above luke warm. Imagine what is going to happen if every house is trying to warm the house up and charge their EV - keep the candles handy!
I agree that to have any chance your house MUST be 100% insulated which is difficult to do if you in an live in an old house. I have neighbour who gutted his house at great expense and fitted a suitable air-sourced heat pump which is enormous on the outside of his house - big motors etc. I feel if we all had this of heat pump the energy used would be a big challenge to the grid.
If I were to go along this line it would have to be a ground-sourced heat pump and preferably put it down a colliery - they always came the surface sweating!
I agree that to have any chance your house MUST be 100% insulated which is difficult to do if you in an live in an old house. I have neighbour who gutted his house at great expense and fitted a suitable air-sourced heat pump which is enormous on the outside of his house - big motors etc. I feel if we all had this of heat pump the energy used would be a big challenge to the grid.
If I were to go along this line it would have to be a ground-sourced heat pump and preferably put it down a colliery - they always came the surface sweating!
John Brown
Freeloading Social media influenza
I would imagine that 100% insulated is not just difficult, but impossible. Probably more feasible to get an infinitely large bike pump.
Terry - Somerset
Established Member
The focus on air source heat pumps seems heavily weighted towards wet systems which can be disruptive and costly unless a new build. There seem to be two approaches.
A wet system retains radiators/underfloor for space heating. As the temperature of the water from an ASHP (45-50C) is below that normally supplied by a gas boiler (~75C), existing radiators are likely to be too small to provide adequate heating in cold weather. Changes to radiators and/or installation of underfloor heating can be expensive.
The alternative seems to be a split system which replaces radiators with high level fan units to provide heating and cooling. Installation should be cheaper and relatively unobtrusive. Radiators can be removed, individual fan units are probably easier to control and more efficient.
A hydrobox can provide hot water for baths and showers water - 40-43C is usually regarded as adequate. Legionnaires may require additional electric heating once a week.
Based on recent bills, water heating is 10-20% of total gas consumption in winter. The capacity of a hydrobox to heat and store hot water is much less than that required for space heating.
I have been contemplating replacing my existing fairly aged GCH system with ASHP. I need to understand whether the alternative split system + hydroxbox ia sensible.
A wet system retains radiators/underfloor for space heating. As the temperature of the water from an ASHP (45-50C) is below that normally supplied by a gas boiler (~75C), existing radiators are likely to be too small to provide adequate heating in cold weather. Changes to radiators and/or installation of underfloor heating can be expensive.
The alternative seems to be a split system which replaces radiators with high level fan units to provide heating and cooling. Installation should be cheaper and relatively unobtrusive. Radiators can be removed, individual fan units are probably easier to control and more efficient.
A hydrobox can provide hot water for baths and showers water - 40-43C is usually regarded as adequate. Legionnaires may require additional electric heating once a week.
Based on recent bills, water heating is 10-20% of total gas consumption in winter. The capacity of a hydrobox to heat and store hot water is much less than that required for space heating.
I have been contemplating replacing my existing fairly aged GCH system with ASHP. I need to understand whether the alternative split system + hydroxbox ia sensible.
John Brown
Freeloading Social media influenza
How does the heat get to these high level fan units? Do you need ducting?
That’s not how it works - the air is the heat to turn a refrigerant liquid into gas (think a big fridge) and then the reverse is done by a plate heat exchanger with water - essentially the heat / cool cycle is in the ASHP and at which point the warm water ends up in the house system. The issue is you need a lot of air as the specific heat capacity of air is very low (ie amount of heat it stores) so that is why there are very large coils and big fans used.
Relative temperature isn’t important - you need to compare the temperature against the boiling points of the refrigerant gas and outside air, the heat “available” in air at -10°C vs +5°C - if you use the Kelvin scale for temperature (which is how engineering does it) then it’s about 6% difference
Never been a case of Legionnaires in the UK in domestic water systems in reported history. It is a hangover from old tank in the attic / open systems so if you have an unvented system supplied by a chlorinated water supply then your risk is nil. The Hydrobox is an expensive alternative to a standard unvented tank with an immersion heater for the times you need more hot water capacity
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