Back in the late '80s I did controls for two primary schools with heat pump and oil boiler combined systems. If the HP couldn't maintain the required flow temp, the boiler kicked in with a mixing valve to mix boiler circuit into the low grade circuit. If that couldn't keep up with building demand, the HP shut down and the boiler could drive the heating circuit up to full temperature.
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prepman
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With low temp design it tends to be done in stages using different refrigerants. Problem with ambient heat extraction, as you say it's too variable.
Also you want more heat the colder it goes. I remember -18C (in 1982?)
We had -17.5°C a couple of years ago, and -16°C last December. Those were relatively short spells in otherwise mild Winters. I can't help wondering how people with ASHPs will get on if we have a cold season, like the year it didn't get above 0°C day or night for the whole of February.
addjunkie
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Itll just be another government uturn….bit like, lets everyone buy a diesel,ooooo no lets all go petrol….oh no leccy….oh no windpowered auto driving cubes….
Trouble is that as you get older and see more of these uninformed whims you start to realise that making real positive change is like turning the titanic.
Erie Fred
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we get -20f in feb. most years, last's maybe 2 weeks max.
One year we had -38f and I got a new manager trainee from Texas on that day (it was a wed.)
I offered to loan her my hat and gloves, she insisted that she didn't want to mess up her hair.....I explained that
-38f was no laughing matter, and if she fell in the snowbank on the way to her car, she might freeze to death.
I also suggested that we check her car's antifreeze level, as I don't know just what they do in Texas,
some places down south run straight water.
She never really came off her high horse, even though we tried to honestly help her.
gaz1
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i just see it as more for there buddies and friends all in the best interests of in there back pockets with there schemes and grants
there grants are creamed from just about everyone
Whatever it is, it is not going to solve climate change! But a lot of people will get led down wrong paths in the process of what is being forced upon people.
What bugs me is that I worked in the energy saving industry in the late '80s to early '90s, mostly driven by price saving. That industry simply collapsed as energy costs didn't continue to rise as feared. Nobody cared a hoot until it came back under the carbon saving banner.
Imagine what could have been achieved if energy saving had been on the agenda for those 20 years. Even now there seems to be a view that it doesn't matter how much is used so long as it's electric. Hence even entry level electric cars with 200HP motors.
Imagine what could have been achieved if energy saving had been on the agenda for those 20 years. Even now there seems to be a view that it doesn't matter how much is used so long as it's electric. Hence even entry level electric cars with 200HP motors.
HughF
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DIY ASHP retrofit in a '46 end of terrace with a 50mm cavity - rads in the house, ufh in the extension.
Works brilliantly and costs less in electric than we were spending before on gas, for a larger house with greater comfort. Win-Win
Works brilliantly and costs less in electric than we were spending before on gas, for a larger house with greater comfort. Win-Win
RaceDiagnostics
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Second log delivery of the season, the first delivery of 1.7m3 was of larch and has lasted 2 months and cost £160. This time I went with birch which was a lot more expensive at £240. Will be interesting to see how it differs, gut feel says I'll go back to larch.......
That is about 700kg of dry wood.
This gives approx 3000kw/h of energy if dry. Not much different between any of the woods for the same weight - not volume of course.
At £240 = £0.08 per kw/h
At £160 = £0.05 per kw/h
Kerosene is about £0.05 per kw/h
Gas about £0.06p per kw/h
Electric - £0.24 per kw/h
So wood is still viable - much more so if it is free
JOEPRO
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That is about 700kg of dry wood.
This gives approx 3000kw/h of energy if dry. Not much different between any of the woods for the same weight - not volume of course.
At £240 = £0.08 per kw/h
At £160 = £0.05 per kw/h
Kerosene is about £0.05 per kw/h
Gas about £0.06p per kw/h
Electric - £0.24 per kw/h
So wood is still viable - much more so if it is free
Do your gas and oil figures allow for system loses and what % efficiency boilers?
It matters as alot of people don't take this into account when comparing fuels.
Onoff
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Not just insulated but with a good degree of air tightness too. Then with air tightness comes considering ventilation like MVHR.
Obviously gas and oil boilers are more efficient than wood burners.
Using kerosene my office heating now costs £200 a month compared to £700 a month electricity.
Onoff
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I wonder where it is all going to end. There are a lot of people going the ASHP route where the fabric of the building is unsuitable or compromised. If they can afford the electricity then box ticked and they carry on or they top it up with fossil fuel.
Likewise mass builders fudging insulation and airtightness results. Do the show house properly and sod the rest.
ASHP can and does work superbly if a fabric first approach is taken.
I still worry about the fragility of our power grid given the things going on at the moment. Once everyone and everything "goes electric" no prizes where the weak points are.
Likewise mass builders fudging insulation and airtightness results. Do the show house properly and sod the rest.
ASHP can and does work superbly if a fabric first approach is taken.
I still worry about the fragility of our power grid given the things going on at the moment. Once everyone and everything "goes electric" no prizes where the weak points are.
JOEPRO
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This tells me you don't understand the concept but that's OK.
Room heat wood burners are considerably more efficient than conventional oil boikers for example and also does not require system losses to be factored in.
I understand how to work out per unit energy costs exactly based on a specific brand and model of boiler for example.
Our last office was sold the "Gas is cheaper" lie by suppliers and plumbers. Installed the system then wondered why it wasn't saving anything. I did a calculation taking into account system cost and per unit energy costs and as a matter of fact our old conventional oil boiler was cheaper to run. Gas company agreed with my calcs but it was too late then.
Are airtight buildings good for people's health though I wonder?
I think I can grasp the concept far better than many thanks
I run a large woodburner very hard. I have a modernish oil boiler and an oil fired aga. I also run electric heating and several Chinese diesel heaters along with a kerosene inverter heater so I have plenty of experience.
