The lowdown on heat pumps

[menthe]

I'd like to investigate installing one of these.  So come on, all you techy types who know about these things.  Take pity on one who is almost totally ignorant.  Tell me all...what different types, pros and cons, prices and savings or no savings worth having, what offers are out there, how can I be sure I won't end up with a white elephant.

The first thing that worries me is that I don't like the look of those attached to the exterior of houses and, if they are low down, whether a passing dog would treat it like a lamp post.  If a lot of disturbance is involved in the installation, I think I'd just as soon wait a bit and start looking more closely at other people's so I'd at least have an idea of whether I actually want to disfigure an outside wall.

[Harnser]

The first question to ask is "Why do you think you need a heat pump"

In other words, what are you trying to achieve?

[menthe]

I blush to tell you my answer.  I have been receiving phone calls and have had an attachment to my edf electricity bill about these things.  So, I thought I'd just do some research.  After all, that's the first step, isn't it?

[Lori]

We had one at the rental house in the Vaucluse.  Horrible !!  It had been installed just before we rented the house, so it was brand new.  The electrical circuit breaker to the house could not cope with the power need of the heat pump, so we lost power continuously.  Once we increased to an 18kw circuit breaker (for a 100 m2 house !!!!!) at a huge increase in cost, we didn't lose power too often.  However, the system couldn't heat the house when the temperature dropped below around double digits.  We'd have to crank it WAY up and the cost was astronomical.

I gather the cost to install it wasn't cheap either.

We decided after 1.5 years with that horrible system, we would never purchase one.  We've since spoken with other folks who had similar experiences.

Good luck Menthe.  I gather a lot depends on the type of house you are trying to heat and the exact system you are considering installing.

 

 

[menthe]

Thanks, Lori.  After your post, I have dropped the idea.🙂

[Polarengineer]

Maybe Lori's apartment was a good example of a poor design and installation. If you already have underfloor heating, a heat pump heated hot water tank would save you money, as the heat from your house could be used for the source of heat for the heat pump. You would need a pipe through a wall to remove the cold air from the heat pump.

If you have radiators, they will be too small to run on this system as the temperature would be a bit lower than from a fired boiler.

The theory is that for every kW energy input, you should get 4kW energy output, but this applies if the temperature output is about 40ºC. Higher temperatures are achieved usually with an additional electric element.

Using outside air as the heat source requires those fan units outside which can be raised away from dogs legs or cats bums, but then they are really in your face. Ground source, where using natural soil temperature requires a geostudy and a lot of digging to lay heat transfer pipes. 

Indoor wall mounted AC units may be a good alternative when you are sure they are the reversible types that also heat the air for winter as well as cool for summer.

If you have a very well insulated house and a good ventilation system throughout, then a 500W dehumidifier will keep a room comfortable and give a constant supply of pure water for the garden (or battery or just to drink).

I'm sure the experts will now jump in with contrary explanations, I hope so, then we will all benefit.

[menthe]

Thank you very much indeed, Polarengineer, for explaining it all so well😃

From the information on your post, I don't think we would benefit from a heat pump. From all the different  perspectives you have so explicitly pointed out.

No radiators, underfloor heating, boiler etc. but we do have a dehumidifier and I do use the water on my geraniums...so I will score 1 point for myself!