The little pipes aren't used now but loads of houses have them . I'm not an expert so I can only go on what I am told and this BBC programme certainly said heat pumps wouldn't work well with little pipes. I can't afford to change so it makes no difference to me!
The little pipes aren't used now but loads of houses have them . I'm not an expert so I can only go on what I am told and this BBC programme certainly said heat pumps wouldn't work well with little pipes. I can't afford to change so it makes no difference to me!
They were fashionable in the 1970s. They have sometimes been used in older houses because they can be threaded through small gaps in houses not designed with pipes in mind. In hard water areas they are a nightmare so will often have already been replaced. They are not common.
Quoting myself from the end of last year, last time someone made the same comment: "... boilers produce water at a high temperature. Most domestic systems are designed for around 80C flow (from the boiler) and 70 return (back to the boiler) at peak heating. Some newer systems will be designed for a 80 flow and 60 return. Heat pumps work best at lower flow and return temperatures - 45 flow and 25 or 30 return.
The size of the pipework is set by the difference in the flow and return temperatures so 10C for the traditional boiler, 20C for a modern one, 15 or 20C for a heat pump - basically all around the same. The smaller the difference, the higher the water flow rate has to be for the same amount of heating. It's very unlikely that a heat pump would need more water flowing than a boiler, so the pipes are more likely to be oversized than undersized and are probably fine."
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
I have read / heard (various sources) that air source heat pumps are just not that effective when they're retro-fitted. My understanding is that they are most effective when fitted in a highly insulated property and preferably using underfloor heating to attain a constant comfortable ambient temperature without hot spots and cold spots.
All heating systems are more effective when installed in a well insulated house. Heat pumps are particularly suitable for underfloor heating because underfloor heating has to operate at a lower flow temp to avoid cracking the concrete/tiles and heat pumps are happiest at the same temps. That is not the same as saying heat pumps work better with underfloor heating - they work fine with radiators and are no more prone to 'hot spots and cold spots' than boilers using radiators.
I have read / heard (various sources) that air source heat pumps are just not that effective when they're retro-fitted. ... Ground source heat pumps seem to get a better press but (my understanding) they require either a substantial network of pipes to be laid (and most people don't have the land/money) or a deep bore ( ditto cost and not all geology is suitable).
There is no difference between ground source and air source as far as the heating system in the house is concerned. The difference is that ground source need a lot of buried pipework in the ground outside and air source have a big fan on the front. Operating temps and all the rest of it are the same. You are correct in that ground source are expensive because the ground pipes cost a lot of money (our borehole for ours cost about the same as the heat pump itself). In most cases, air source will be cheaper and no less effective.
It does seem nearly criminal if new houses are now being built without solar panels, efficient ground source heat pumps and attendant heating systems, very high levels of insulation etc. It is surely much easier (and therefore cheaper) to engineer all these things in from scratch.
Building regulations are changing this summer and either solar panels or heat pumps will become more common - though not compulsory. There's another change planned for 2025 when it won't be allowed to put in gas boilers in a new house, unless the gas lobby manage to nobble the Government between now and then (likely). You are certainly right that it's much cheaper to build these things in from new rather than to try to retrofit them later. A number of Local Authorities are trying to bring in their own local planning policy to make that a requirement (Cambridge, Lincoln, Cornwall, for examples I know about). The national Government is have a good go at preventing them from enacting these rules.
I read a report of somebody who'd bought a 1930's bungalow and paid a premium because it was fitted with a heat pump (think it was an air one). The bungalow was reasonably well insulated but unreasonably cold in winter. She changed a couple of radiators for bigger ones and upgraded the insulation. She was still cold. She eventually spent even more £££s getting rid of the pump and putting a gas boiler in.
It's difficult to say why that would be without knowing the specifics. In many cases, the reason old houses are a problem is that they are very leaky, so air comes in round the windows, under the roof, through the walls and so on. This makes the heat demand very 'peaky'; on a calm day it will need far less than on a windy day. The heat pump is a lower intensity type of heating and it is less able to ramp up the heat quickly when the temperature drops suddenly. When people say the house needs to be well insulated to work with a heat pump, what they really mean is it needs to be reasonably draught-free. In a very draughty old house, it can be helpful to install the heat pump without removing the boiler, so you use the heat pump nearly all the time and then the boiler kicks in just on the coldest days. These systems are called 'hybrid'. The CCC is arguing that hybrid systems should be adopted as fast as possible wherever a simple heat pump cannot be used.
The size of radiators can be a genuine problem. In most cases, the radiators in a reasonably modern house will not have been chosen to match the amount of heat needed, but just 'by eye' as to what looks about right to the plumber for that room, or even the biggest one they could fit in the space. So a lot of them are much bigger than they need to be and will be fine with the lower output from the heat pump. Some won't though - and the radiators (not the pipes - entirely different issue) will need to be replaced. It's not a rule that radiators are always too small, it's a risk that some may be and it needs to be checked.
The lady in that report would probably have been better advised to get a thermal image survey done of her house and mastic gun to seal up the gaps.
Ultimately, a better insulated, less draughty house will cost less to heat, however you heat it. Gas is currently effectively subsidised in the UK. It won't continue to be. Electricity prices are currently tied to gas prices because we are still quite heavily reliant on gas generation on the network. That reliance is diminishing quite fast - the suppliers own self interest is driving that. Gas and oil prices will always go up. Electricity may eventually plateau.
But I cannot guarantee that - it's just my bet. Which is why I have a heat pump and a lot of loft insulation in my house
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
Brilliantly put and extremely interesting @raisingirl - even I can follow that. Many thanks for clarifying what to many people is a complicated subject.
My house is the end of a terrace of three, built in the 1870's. It doesn't have cavity walls or standard size windows so no double glazing. There's quite a lot of movement on the clay soil so we have underpinning and a good many draughts. The central heating probably went in during the 1970's with a back boiler which lasted nearly 50 years and would still be running had spare parts been available. Now there is a boiler with a life expectancy of 5 years.
There are many homes like mine in my village and the government must shake its head at the task of making them environmentally friendly, but short of knocking them down, there's not much you can do. However, we don't actually use more energy than many modern homes so the Victorians must have got something right.
@raisingirl - thank you for that detailed response to my post. It's certainly given me food for thought about whether we should consider swapping to an air source pump system.
Certainly agree about insulating properties. Over the last 18 months we've replaced all our wooden doors and windows. They were nearly 30 years old and the usual builder's cheapest-option-wood. Although double glazed they were not to the standard of modern double glazing. Many were warped, some were a bit rotten and one or two leaked in driving rain. In howling winds they were draughty and it was amazing how the wind whistling through a north facing keyhole could lower the temp of a whole room.
We have been delighted with how much warmer and quieter the house has been this year. Hall thermostat has been set to 17.5C all winter with just a nudge up a degree or two for a couple of hours on the coldest evenings.
One question for you. Is an air source pump really up to the job if it's really cold outside - say sub zero for a run of several days? It doesn't happen often but we do get spells like that and that's when you need a good heating system - especially for my cold blooded husband. He's going to take a lot of convincing that anything sucking in air at -5C is going to keep him warm enough...
I'm coming to the conclusion that what we really need in this country are more very good, knowledgable engineers who will can give comprehensive, realistic and unbiased advice to potential customers like me. I don't want a salesman promising the earth. I want a tailored, honest appraisal of what an air source system could mean for us.
Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down
One question for you. Is an air source pump really up to the job if it's really cold outside - say sub zero for a run of several days? It doesn't happen often but we do get spells like that and that's when you need a good heating system - especially for my cold blooded husband. He's going to take a lot of convincing that anything sucking in air at -5C is going to keep him warm enough...
I'm coming to the conclusion that what we really need in this country are more very good, knowledgable engineers who will can give comprehensive, realistic and unbiased advice to potential customers like me. I don't want a salesman promising the earth. I want a tailored, honest appraisal of what an air source system could mean for us.
The newest ones are able to continue to heat to the same temperature down to about minus 14C outside. The main market where they are sold in greatest numbers are in Sweden, Austria, Germany and Switzerland - none of them famous for their temperate winters - so they have been engineered for those conditions. They become less efficient at those temperatures, but a heat pump at it's absolute worst is still more efficient than a gas boiler at its absolute best. Ground source never has to deal with these problems because the ground never gets that cold in the UK, but it does have its own issues. We have ground source here, but I don't think I'd recommend it generally for an individual house - the advantages don't pay for the extra cost. It's good for blocks of flats, where air source is often more difficult to find a place to put it.
There's an organisation called the AECB - the Association for Environment Conscious Building - it's an independent organisation (not a Quango) and it provides training for contractors and designers to design and build better, more energy efficient buildings (there are others who do this as well, of course). They have begun to run courses called 'Retrofit Co-ordinators', with the aim of teaching industry professionals to advise people on how to do this, taking into consideration all the technical issues. The hard parts are actually not really the heating, but the fabric improvements, avoiding creating mould and damp problems or worse (Grenfell tower was a retrofit). The hope is to have a register of people who are trained and certified and who are not selling the products, who can come to your house, do a survey and give you an honest assessment of what's possible. They're not there yet but it's beginning to be organised.
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
Posts
Quoting myself from the end of last year, last time someone made the same comment: "... boilers produce water at a high temperature. Most domestic systems are designed for around 80C flow (from the boiler) and 70 return (back to the boiler) at peak heating. Some newer systems will be designed for a 80 flow and 60 return. Heat pumps work best at lower flow and return temperatures - 45 flow and 25 or 30 return.
The size of the pipework is set by the difference in the flow and return temperatures so 10C for the traditional boiler, 20C for a modern one, 15 or 20C for a heat pump - basically all around the same. The smaller the difference, the higher the water flow rate has to be for the same amount of heating. It's very unlikely that a heat pump would need more water flowing than a boiler, so the pipes are more likely to be oversized than undersized and are probably fine."
“It's still magic even if you know how it's done.”
Heat pumps are particularly suitable for underfloor heating because underfloor heating has to operate at a lower flow temp to avoid cracking the concrete/tiles and heat pumps are happiest at the same temps. That is not the same as saying heat pumps work better with underfloor heating - they work fine with radiators and are no more prone to 'hot spots and cold spots' than boilers using radiators.
There is no difference between ground source and air source as far as the heating system in the house is concerned. The difference is that ground source need a lot of buried pipework in the ground outside and air source have a big fan on the front. Operating temps and all the rest of it are the same. You are correct in that ground source are expensive because the ground pipes cost a lot of money (our borehole for ours cost about the same as the heat pump itself). In most cases, air source will be cheaper and no less effective.
Building regulations are changing this summer and either solar panels or heat pumps will become more common - though not compulsory. There's another change planned for 2025 when it won't be allowed to put in gas boilers in a new house, unless the gas lobby manage to nobble the Government between now and then (likely). You are certainly right that it's much cheaper to build these things in from new rather than to try to retrofit them later. A number of Local Authorities are trying to bring in their own local planning policy to make that a requirement (Cambridge, Lincoln, Cornwall, for examples I know about). The national Government is have a good go at preventing them from enacting these rules.
Yes, that is true. But complicated is not necessarily impossible, and the degree of difficulty varies a lot.
It's difficult to say why that would be without knowing the specifics.
In many cases, the reason old houses are a problem is that they are very leaky, so air comes in round the windows, under the roof, through the walls and so on. This makes the heat demand very 'peaky'; on a calm day it will need far less than on a windy day. The heat pump is a lower intensity type of heating and it is less able to ramp up the heat quickly when the temperature drops suddenly. When people say the house needs to be well insulated to work with a heat pump, what they really mean is it needs to be reasonably draught-free. In a very draughty old house, it can be helpful to install the heat pump without removing the boiler, so you use the heat pump nearly all the time and then the boiler kicks in just on the coldest days. These systems are called 'hybrid'. The CCC is arguing that hybrid systems should be adopted as fast as possible wherever a simple heat pump cannot be used.
The size of radiators can be a genuine problem. In most cases, the radiators in a reasonably modern house will not have been chosen to match the amount of heat needed, but just 'by eye' as to what looks about right to the plumber for that room, or even the biggest one they could fit in the space. So a lot of them are much bigger than they need to be and will be fine with the lower output from the heat pump. Some won't though - and the radiators (not the pipes - entirely different issue) will need to be replaced. It's not a rule that radiators are always too small, it's a risk that some may be and it needs to be checked.
The lady in that report would probably have been better advised to get a thermal image survey done of her house and mastic gun to seal up the gaps.
Ultimately, a better insulated, less draughty house will cost less to heat, however you heat it. Gas is currently effectively subsidised in the UK. It won't continue to be. Electricity prices are currently tied to gas prices because we are still quite heavily reliant on gas generation on the network. That reliance is diminishing quite fast - the suppliers own self interest is driving that. Gas and oil prices will always go up. Electricity may eventually plateau.
But I cannot guarantee that - it's just my bet. Which is why I have a heat pump and a lot of loft insulation in my house
“It's still magic even if you know how it's done.”
The central heating probably went in during the 1970's with a back boiler which lasted nearly 50 years and would still be running had spare parts been available. Now there is a boiler with a life expectancy of 5 years.
There are many homes like mine in my village and the government must shake its head at the task of making them environmentally friendly, but short of knocking them down, there's not much you can do. However, we don't actually use more energy than many modern homes so the Victorians must have got something right.
Certainly agree about insulating properties. Over the last 18 months we've replaced all our wooden doors and windows. They were nearly 30 years old and the usual builder's cheapest-option-wood. Although double glazed they were not to the standard of modern double glazing. Many were warped, some were a bit rotten and one or two leaked in driving rain. In howling winds they were draughty and it was amazing how the wind whistling through a north facing keyhole could lower the temp of a whole room.
We have been delighted with how much warmer and quieter the house has been this year. Hall thermostat has been set to 17.5C all winter with just a nudge up a degree or two for a couple of hours on the coldest evenings.
One question for you. Is an air source pump really up to the job if it's really cold outside - say sub zero for a run of several days? It doesn't happen often but we do get spells like that and that's when you need a good heating system - especially for my cold blooded husband. He's going to take a lot of convincing that anything sucking in air at -5C is going to keep him warm enough...
I'm coming to the conclusion that what we really need in this country are more very good, knowledgable engineers who will can give comprehensive, realistic and unbiased advice to potential customers like me. I don't want a salesman promising the earth. I want a tailored, honest appraisal of what an air source system could mean for us.
There's an organisation called the AECB - the Association for Environment Conscious Building - it's an independent organisation (not a Quango) and it provides training for contractors and designers to design and build better, more energy efficient buildings (there are others who do this as well, of course). They have begun to run courses called 'Retrofit Co-ordinators', with the aim of teaching industry professionals to advise people on how to do this, taking into consideration all the technical issues. The hard parts are actually not really the heating, but the fabric improvements, avoiding creating mould and damp problems or worse (Grenfell tower was a retrofit). The hope is to have a register of people who are trained and certified and who are not selling the products, who can come to your house, do a survey and give you an honest assessment of what's possible. They're not there yet but it's beginning to be organised.
“It's still magic even if you know how it's done.”