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!

[ssomon]

First of all, don't drink the condensed water produced by a dehumidifier or by any air cooling device. It contains a concentrate of all sorts of nasty things from the air in the living space, including body effluents and particles from people and animals, microbes, bacteria, other small particles, etc.

As noted by Polar Engineer, problems are almost exclusively due to poor design and installation, all too common in my own experience, so, before thinking of installing any sort of heating, get the house well insulated, then have the necessary calculations done to determine what size and type of unit is required.

The latest heat pumps can cope with lower temperatures than those experienced by most people in France, but must be correctly sized. Their efficiency falls with low temperatures, so a larger unit is required for a given space as the outside temperature falls.

Here is some fairly current and useful information: https://aquariushomeservices.com/blog/heat-pump-temperature-range/   There is plenty more available.

Our old, probably 1980's air source reversible air conditioning units, which were in the house when we bought it, did not provide enough heat when the outside temperature dropped below about 5 C, so we used our pellet stove after that.

Two years ago the price of pellets went through the roof, so I replaced the two old units, with three larger ones.

The living area of the house is about 120 sq metres. The two original units, were rated at 9,500 BTU/Hr (2.78 kW) each; the new units, also air source, are the inverter type, rated at 12,000 BTU/Hr (3.5 kW) each.

Since installing them we have had no extreme weather, and have needed to run only two units in both summer and winter, but we are prepared for the worst.

Edited September 28 by ssomon

[menthe]

Thank you, ssomon, how like you to know all the details and more about stuff like this🙂

I will indeed look at your link and be a bit more methodical about my own researches. 

[ssomon]

Incidentally, our electricity bill increased from €1279 for 2021 to €1523 for 2022 and €1496 for 2023, but we are saving at least €220 per year - at the old prices, by not buying pellets.

We also escape the weekly cleaning of the stove and the cost of the annual check and repairs and chimney sweeping.

We didn't mind this when the price of pellets made the stove economical, so we could have the house a couple of degrees warmer than now, but these days we just put on a bit more clothing and manage with it at around 20 C.

Although the prices of pellets are now down to around the old levels, we don't care to be at the mercy of profiteering producers, preferring to rely on energy sources which are stabilised by the government.

 

 

Edited September 28 by ssomon
more detail

[Polarengineer]

I am not promoting the drinking of dehumidifier condensate, but to compare and allow one to decide, one must remember that all that possible room air contamination is already being breathed in. However, the condensate is completely free of the micro and nano contaminates of tap water. There was a worrying report in the news of the state of river water where remnants of medicines and drugs, microplastics an PFAS’ are entering the water, namely antidepressants getting converted to toxins in tap water. I doubt bottled water is any better.

https://edu.rsc.org/science-research/antidepressants-in-waste-water-may-cause-potent-tap-water-toxin/4011518.article

https://www.bbc.com/news/articles/cly93ggx88po

[Lori]

Honestly, the more we find out about the chemicals/plastics in the food/drinks we ingest and the earth in which we grow our food crops, it is a miracle we are all still walking.

Seems nothing is safe.

 

 

[Lehaut]

23 hours ago, Lori said:

Seems nothing is safe.

Indeed they are everywhere

https://www.theguardian.com/environment/article/2024/may/20/microplastics-human-testicles-study-sperm-counts