People Saying Heat Pumps are Rubbish - Are They?

subjecttocontract

I was under the impression that there are two main types. Air to air and air to water. Most of this forum discussion has been about air to water systems but my limited experience is with air to air systems which I find are absolutely brilliant.

benson1980

MeteredOut said:

grumpypensioner said:

I wonder why so many forumites are so defensive about their installation of heat pump systems? Every new technology has problems as well as great benefits. Why don't we list the pros and cons honestly to help future purchasers choose? Opinions?

Its quite similar to the "EV debate". There's a lot of misinformation that those who have EVs (and in this case, have heat pumps) are able to debunk.

In the case of Heat Pumps, the starting position I hear is that any house can be converted to work with a heat pump with running costs lower than or equivalent to a gas boiler and that any negative reports we see are due to badly spec'd/installed/configured systems.

I'm not convinced it is a simple as that.

What can never be defined without more detailed investigation is what work is needed to get any individual house "heat pump ready" so that running costs are lower or equivalent to a gas boiler.

eg, I have a house with a large floor space with underfloor heating downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - i don't believe simply swapping out the gas boiler for a heat pump would suffice.

It is actually pretty simple. You just need sufficient emitters to cater for a design [flow] temperature of 50 or below, and possibly some pipework upgrades. The reason 50 is quoted is because this usually gives a SCOP of around 3.8 which one might consider the break even point with a gas boiler- in reality it will probably be less. 

The less well insulated the house is, the bigger the emitters need to be. K2 and K3 radiators can emit a lot of heat and it might just be a case of changing radiators from a K1 to a K2 (or perhaps K3) in certain rooms. Quite often the pipe centres (i.e. width of radiator) can remain the same thus meaning minimal disruption. 

NedS

There is a great scheme called Visit A Heat Pump being operated here:

https://www.visitaheatpump.com/

If you are considering a heat pump, or just want to find out more first hand information and real world experience from someone who has one, I would strongly suggest visiting an install locally and speaking with the owner.

michaels

benson1980 said:

MeteredOut said:

grumpypensioner said:

I wonder why so many forumites are so defensive about their installation of heat pump systems? Every new technology has problems as well as great benefits. Why don't we list the pros and cons honestly to help future purchasers choose? Opinions?

Its quite similar to the "EV debate". There's a lot of misinformation that those who have EVs (and in this case, have heat pumps) are able to debunk.

In the case of Heat Pumps, the starting position I hear is that any house can be converted to work with a heat pump with running costs lower than or equivalent to a gas boiler and that any negative reports we see are due to badly spec'd/installed/configured systems.

I'm not convinced it is a simple as that.

What can never be defined without more detailed investigation is what work is needed to get any individual house "heat pump ready" so that running costs are lower or equivalent to a gas boiler.

eg, I have a house with a large floor space with underfloor heating downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - i don't believe simply swapping out the gas boiler for a heat pump would suffice.

It is actually pretty simple. You just need sufficient emitters to cater for a design [flow] temperature of 50 or below, and possibly some pipework upgrades. The reason 50 is quoted is because this usually gives a SCOP of around 3.8 which one might consider the break even point with a gas boiler- in reality it will probably be less. 

The less well insulated the house is, the bigger the emitters need to be. K2 and K3 radiators can emit a lot of heat and it might just be a case of changing radiators from a K1 to a K2 (or perhaps K3) in certain rooms. Quite often the pipe centres (i.e. width of radiator) can remain the same thus meaning minimal disruption. 

Agree with all that but wonder where you get the max flow 50c gives a 3.8 SCOP data point?  I would suspect that you would need 45C for that sort of SCOP?

Also it is not always simply a case of upgrading emitters, it may also be that the pipe diameters are inadequate to achieve the required flow rates.

QrizB

MeteredOut said:

eg, I have a house with a large floor space with water underfloor heating throughout downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - my (admittedly fairly rudimentary to date) look into this makes me believe simply swapping out the gas boiler for a heat pump would never suffice.

With wet underfloor heating downstairs, you should be an easier case for a heat pump than most.

You might need larger radiators upstairs.

benson1980

michaels said:

benson1980 said:

MeteredOut said:

grumpypensioner said:

I wonder why so many forumites are so defensive about their installation of heat pump systems? Every new technology has problems as well as great benefits. Why don't we list the pros and cons honestly to help future purchasers choose? Opinions?

Its quite similar to the "EV debate". There's a lot of misinformation that those who have EVs (and in this case, have heat pumps) are able to debunk.

In the case of Heat Pumps, the starting position I hear is that any house can be converted to work with a heat pump with running costs lower than or equivalent to a gas boiler and that any negative reports we see are due to badly spec'd/installed/configured systems.

I'm not convinced it is a simple as that.

What can never be defined without more detailed investigation is what work is needed to get any individual house "heat pump ready" so that running costs are lower or equivalent to a gas boiler.

eg, I have a house with a large floor space with underfloor heating downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - i don't believe simply swapping out the gas boiler for a heat pump would suffice.

It is actually pretty simple. You just need sufficient emitters to cater for a design [flow] temperature of 50 or below, and possibly some pipework upgrades. The reason 50 is quoted is because this usually gives a SCOP of around 3.8 which one might consider the break even point with a gas boiler- in reality it will probably be less. 

The less well insulated the house is, the bigger the emitters need to be. K2 and K3 radiators can emit a lot of heat and it might just be a case of changing radiators from a K1 to a K2 (or perhaps K3) in certain rooms. Quite often the pipe centres (i.e. width of radiator) can remain the same thus meaning minimal disruption. 

Agree with all that but wonder where you get the max flow 50c gives a 3.8 SCOP data point?  I would suspect that you would need 45C for that sort of SCOP?

Also it is not always simply a case of upgrading emitters, it may also be that the pipe diameters are inadequate to achieve the required flow rates.

The MCS product database. Vaillant arotherm plus for example- 3.85 at 50.

Re: pipework yes indeed hence why I mentioned possible pipework upgrades.

Nick_Dr1

MeteredOut said:

In the case of Heat Pumps, the starting position I hear is that any house can be converted to work with a heat pump with running costs lower than or equivalent to a gas boiler and that any negative reports we see are due to badly spec'd/installed/configured systems.

I'm not convinced it is a simple as that.

What can never be defined without more detailed investigation is what work is needed to get any individual house "heat pump ready" so that running costs are lower or equivalent to a gas boiler.

eg, I have a house with a large floor space with water underfloor heating throughout downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - my (admittedly fairly rudimentary to date) look into this makes me believe simply swapping out the gas boiler for a heat pump would never suffice.

It is as simple as that. The system just needs to be designed such that heat in > heat out. This works for any heat source. Its just more nuanced for heatpumps as they don't crank out large amounts of heat in a short period like an oversized gas boiler.
A heatpump system needs to be designed, by someone who understands what they are doing. This includes understanding heat loss, heat transfer of radiators and heat flow rate though pipes. And that's it.
Get it wrong though and there's nowhere to go. With a gas boiler you normally have excess heat capability to allow for incompetent heat flow design.
What this means is that "standard" houses can have a "standard" design. Unusual houses need bespoke design by someone who knows what they are doing. So it is all about the spec.

grumpypensioner

MeteredOut said:

grumpypensioner said:

I wonder why so many forumites are so defensive about their installation of heat pump systems? Every new technology has problems as well as great benefits. Why don't we list the pros and cons honestly to help future purchasers choose? Opinions?

Its quite similar to the "EV debate". There's a lot of misinformation that those who have EVs (and in this case, have heat pumps) are able to debunk.

In the case of Heat Pumps, the starting position I hear is that any house can be converted to work with a heat pump with running costs lower than or equivalent to a gas boiler and that any negative reports we see are due to badly spec'd/installed/configured systems.

I'm not convinced it is a simple as that.

What can never be defined without more detailed investigation is what work is needed to get any individual house "heat pump ready" so that running costs are lower or equivalent to a gas boiler.

eg, I have a house with a large floor space with water underfloor heating throughout downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - my (admittedly fairly rudimentary to date) look into this makes me believe simply swapping out the gas boiler for a heat pump would never suffice.

You make a very good point. I have been unable to find out the actual cost of someone's installation - not just a quote. From researching the subject I am not sure that saving money is the main reason for installing a system. It is perhaps a way of helping reduce personal fossil fuel usage by passing the buck onto the national grid. It would need a large unit to replace your gas boiler only to achieve equivalent running costs with a loss of capital - refute that if people can.
I found a bit of a solution, I purchase a standalone air conditioner unit to supplement my old Baxi gas boiler, with a new Wessex 1.47kw 12000 BTU unit from ToolStation (over 200% efficiency) which cost me under £400 installed (needs a standard 10cm wall air duct and drain pipes and just plugs into a 13 amp socket). I switch it on in cold weather and it warms the whole house when needed so that I can reduce the load and temperature of the gas central heating system (and I still have lovely hot water for showers), difficult to quantify but my energy bill has significantly reduced for minimal outlay. I really think that a large single replacement installation is not the solution, apply technology where it fits and compromise.

Spies

My cost was £1300 for everything including 7 radiator swaps, had it not been that price I wouldn't have done it but it's enabled me to get away from gas and use more of my own solar generation which is no bad thing!

It was not about saving money for me so I'm not counting a payback period like I am for my solar panels 

FreeBear

grumpypensioner said:

MeteredOut said:

grumpypensioner said:

I wonder why so many forumites are so defensive about their installation of heat pump systems? Every new technology has problems as well as great benefits. Why don't we list the pros and cons honestly to help future purchasers choose? Opinions?

Its quite similar to the "EV debate". There's a lot of misinformation that those who have EVs (and in this case, have heat pumps) are able to debunk.

In the case of Heat Pumps, the starting position I hear is that any house can be converted to work with a heat pump with running costs lower than or equivalent to a gas boiler and that any negative reports we see are due to badly spec'd/installed/configured systems.

I'm not convinced it is a simple as that.

What can never be defined without more detailed investigation is what work is needed to get any individual house "heat pump ready" so that running costs are lower or equivalent to a gas boiler.

eg, I have a house with a large floor space with water underfloor heating throughout downstairs and traditional radiators upstairs, but fairly poorly insulated, all powered from a 40kW gas boiler. I know it should be possible to get a Heat Pump working, but there's a lot of work to do to get it there - my (admittedly fairly rudimentary to date) look into this makes me believe simply swapping out the gas boiler for a heat pump would never suffice.

 It would need a large unit to replace your gas boiler only to achieve equivalent running costs with a loss of capital - refute that if people can.

For a long while, gas engineers have been installing boilers way bigger than are actually needed. Most houses in the UK only need 6-8kW to heat the place. And if you have a system (or heat only) boiler, 12-18kW is sufficient to heat a tank of water. OK, it might take 45mins to an hour to get up to temperature from cold. Combi boilers on the other hand, should be rated for the maximum cold water flow rate, so you might need a 30kW boiler if you have 12l/min of water.

A very rough rule of thumb to determine the size of a heat pump needed is to take your annual gas consumption (in kWh) and divide it by 2900. But if you are like me and supplement heating with a wood stove, it is going to throw the calculation out. In which case, Heat Geek has a handy rough estimation table -> https://www.heatgeek.com/how-to-size-my-heat-pump-or-boiler-heat-loss-cheat-sheet/