Air source heat pump
- Thread starter ronk
- Start date
At the summit of the picturesque fens
Hello,
Finally a subject I know about (cos I know sod all about cars).
Air source heat pumps are crap! Anything else you would like to know?
Sorry, I take that back. Air source heat pumps are absolutely crap for retro-fitting, they're just crap if you have underfloor heating.
The only heat pump worth having for domestic heating is ground source but it impractical for most situations and even more expensive.
Finally a subject I know about (cos I know sod all about cars).
Air source heat pumps are crap! Anything else you would like to know?
Sorry, I take that back. Air source heat pumps are absolutely crap for retro-fitting, they're just crap if you have underfloor heating.
The only heat pump worth having for domestic heating is ground source but it impractical for most situations and even more expensive.
The main problem is that the equipment sold for domestic heating purposes, ie heating water, is not able to heat water to more than about 55 degrees celcius, meaning you get a very low TD of approximately 35 degrees. Not good for convection or radiant heating.
The second, or possibly the equal first problem is that they are marketed as being "400% efficient" and "for every kW of power you put in you get 4-5 kW of heat". That simply is not the case. OK it is the case if all of the parameters of that efficiency have been met. Put simply, when the ambient temperature is approx 7 degrees celcius or above they will meet that efficiency, although the above still comes into play.
Ambients below 7 degrees, their efficiency drops like a stone, which also results in water temperature doing the same.
They have got to be the only heating technology where the colder it is outside, the worse they work. Sort of defeats the object, don't you think?
They are using equipment for a purpose for which it a). wasn't designed for and b). isn't suitable for.
Our stupid Government have bought into the marketing regarding "green energy", so have jumped on board. Even LABCs are stipulating them in most new builds. It's ridiculous. I recently built my own house and had this very argument with LABC. Luckily, I know what I'm talking about so managed to get them to pass an oil-fired boiler in a new build (I bet not many of those around). My house was still able to make an energy efficiency of an "A".
As soon as hydrogen boilers are up to speed, air source for homes will be a thing of the past.
BTW I have been a highly qualified refrigeration and air conditioning engineer for the past 36 years, so deal with this stuff every day.
The second, or possibly the equal first problem is that they are marketed as being "400% efficient" and "for every kW of power you put in you get 4-5 kW of heat". That simply is not the case. OK it is the case if all of the parameters of that efficiency have been met. Put simply, when the ambient temperature is approx 7 degrees celcius or above they will meet that efficiency, although the above still comes into play.
Ambients below 7 degrees, their efficiency drops like a stone, which also results in water temperature doing the same.
They have got to be the only heating technology where the colder it is outside, the worse they work. Sort of defeats the object, don't you think?
They are using equipment for a purpose for which it a). wasn't designed for and b). isn't suitable for.
Our stupid Government have bought into the marketing regarding "green energy", so have jumped on board. Even LABCs are stipulating them in most new builds. It's ridiculous. I recently built my own house and had this very argument with LABC. Luckily, I know what I'm talking about so managed to get them to pass an oil-fired boiler in a new build (I bet not many of those around). My house was still able to make an energy efficiency of an "A".
As soon as hydrogen boilers are up to speed, air source for homes will be a thing of the past.
BTW I have been a highly qualified refrigeration and air conditioning engineer for the past 36 years, so deal with this stuff every day.
The other major drawback is that they are installed by plumbers, who know absolutely nothing about them. A three day course to make sure they are "legal" is about it.
These "renewable energies" companies are nearly always plumbers jumping on the (very lucrative) bandwagon.
If I had a pound for the number of times I've been asked by plumbers to help them with commissioning on ASHPs I would be a very rich man.
These "renewable energies" companies are nearly always plumbers jumping on the (very lucrative) bandwagon.
If I had a pound for the number of times I've been asked by plumbers to help them with commissioning on ASHPs I would be a very rich man.
Zedebee said:
That's because it's doing the job it was designed to do. The same equipment as yours with a water coil bolted on in place of the fan/coils is an ASHP but the physics of water and air are not the same.
It's like if you stuck a moped engine on a shopping trolley, it could be marketed as the most fuel efficient roadster. And the marketing was so good our Government forced you to buy them. Same scenario as the above.
I can't recall the exact date but no new gas boiler installations will be allowed after 2025 (in new builds). I work in design services for a district council and we will be fitting air source heat pumps in our new builds from now on.
Problems as as above - plus they are three to four times more expensive to run than gas. There is talk of capping electricity prices to make ASHP's more attractive.
Problems as as above - plus they are three to four times more expensive to run than gas. There is talk of capping electricity prices to make ASHP's more attractive.
Pondrew said:
The heating and water in our house is oil fired (with a wood burning stove; heat only for spring/autumn or if we have a panic boiler going down) but I'm fed up of working in the cold in the garage and workshop. I was starting to look at air source heating for the workshop. Are you saying this is OK as air to air - but if I go air to water in large flat cast iron rads it's not worth it?
I don't want heat like in the house - if it will do 7 - 10 degrees C in October to early December and again in Feb until April that's all I need to stop my nuts (all of them) freezing
Wife's daughter has her own swim school, with an 11m x 6m x 1.4m deep pool in an industrial unit. I am her 'maintenance man'. The water is heated to 32 degrees (warm for babies) by an industrial sized air source pump. Fine in summer, but as soon as the outside air drops below about 5 degrees we have to switch on the inline electric heater too. The air source on its own can't get above about 27 degrees.
As for the discussion about plumbers or electricians installing it..................... we had a fault which turned out to be the flow switch failed. A simple flapper that hangs down in the water pipe and indicates when the water is passing it.
Electrician installed a new one but still had the same fault. He gave up and started looking elsewhere. I turned up, turned the flow switch so that the big effin' arrow on it lined up with the water flow and lo and behold..................... :roll:
As for the discussion about plumbers or electricians installing it..................... we had a fault which turned out to be the flow switch failed. A simple flapper that hangs down in the water pipe and indicates when the water is passing it.
Electrician installed a new one but still had the same fault. He gave up and started looking elsewhere. I turned up, turned the flow switch so that the big effin' arrow on it lined up with the water flow and lo and behold..................... :roll:
Zedebee said:
I want to build the heat up so all the machines are warm as well - so I'm not working the lathe with the gearbox full of cold / stiff oil for example or the metal stock I'm using are like blocks of ice to hold - and I'm sick of lying on a cold floor at my age let alone the fact its often too cold to paint. Spot heaters are fine until you move and you can end up with one side of your work hot and the other cold. To my mind constant low level heating will provide a happier working environment. I've read a few sales pitches for air source and they talk about £250 /£300 electric use. I'm sure conventional heating by oil or electric is going to be more than that.
Forgot to say I'm retired so some weeks in autumn and spring I can spend days on end in the workshop.