Heat pumps and noise

[transam]

Ripped out an air source heat pump yesterday

2nd one we have taken out in the last 2 months

Also in the new year a land lord we do a lot of work for is considering taking out 4 in his new build rentals ????

( new build 7 years old )

 

[Rad1o]

And back to the original question after all this rant.

We have a heat pump outside our bedroom window - about 2m into the garden. We hear a faint humming noise even when it is working hard, e.g. when it was -9°C in January. The neighbours do not even know that we have a heat pump. What we do hear is the flow through the pipes as the installer did not bury them into the ground but bracketed them onto the outside walls.
Our house has 15mm pipework, but some new builds have 7 and 8mm pipes with heat pumps.

If you have an poorly insulated house, a heat pump will probably not work well as the temperature gradient / heat loss is quite steep. Insulate your walls first. This is also a bliss for the summers.

 

[robinbanks]

Genuine question. If there was a cold period with temperature at -10 for a week (it happened in 2011/12), how would the ashp system fare?

Fine. 0 degrees is not a magic number to an ASHP; the air still has useful heat energy they can extract. The lower limit is determined by the characteristics of the refrigerant, not water, and any water in the system should have antifreeze added. Any air temperature capable of warming the tefrigerant up can have heat extracted - the cycle they run is:

Compressor compresses gas, heating it
Extra heat is extracted to water
Cold compressed gas is expanded, cooling it
Air is used to warm the expanded gas, heating it, and cooling the air (extracting heat energy from the air)

If the gas is at -30 when it is cold compressed, air at -10 will warm the gas up

--

The efficiency lowers as the temperature drops and you do theoretically reach a point with very low air temperatures and high flow temperatures where a pump is little better than a resistive heater as the efficiency approaches 1 (uses 1 kw of electrical energy to produce 1kw of heat)
Some pumps have resistive heaters built in or can control an aux one

Ripped out an air source heat pump yesterday

2nd one we have taken out in the last 2 months

Also in the new year a land lord we do a lot of work for is considering taking out 4 in his new build rentals ????

( new build 7 years old )

Dare say was mis sold, the system was badly designed and the house was suboptimal.

That it's new means nothing; bad design, shoddy build and ignorant occupants are plentiful in supply and all that's required to make a low level heating system unworkable

You post doesn't contain enough useful facts to be anything more than anecdotal scaremongering/bluster but if you're ripping anything then you're just being a fool about it; remove it carefully, because someone out there willing to put the effort in to make it useful and viable will pay good money for that install second hand

 

[mitch66]

Why would anyone want to spend £12k (5k with the grant ) to save £100 per year

Cos they're mugs. Better still they buy solar, batteries and have a smart meter. Then they can up send at 6p a KWH to there neighbour who pay the grid 50p a KWH for it. They also get a chance to show their virtue to other mugs who give a crap about it.

 

[SimonH2]

So if a uninsulated house is ok with 30kw output gas boiler would it be ok with a 15kw heat pump? I don't know but wonder. A house shown on the TV that had been converted appeared to have a hell of a lot new piping installed.

30kW would heat a house that was either very big or very poorly insulated. These days where combi boilers are the norm, the 30kW boiler is the minimum to get anything vaguely resembling hot water, and it's grossly oversized for the heating.

Heat pumps probably will be when it becomes illegal to fit new boilers. Personally I'm all for it; a monobloc HP paired with a open vent thermal store is completely DIYable, no G3 in sight

Must admit, that's been in my mind - already have a thermal store, had it made with a few spare ports ...

The fun bit is going to be when all these new build shoeboxes need a new boiler, and the owner needs to somehow find room for a hot water cylinder but there's no-where it could go.

Ripped out an air source heat pump yesterday

2nd one we have taken out in the last 2 months

Also in the new year a land lord we do a lot of work for is considering taking out 4 in his new build rentals ????

( new build 7 years old )

Let me guess - poor EPCs ?
That's one current problem, a HP is classed as electric heating, and as the assessment system only considered assumed costs, electric heating will lower the EPC rating. Until they revamp the assessment system, there's a big disincentive to fit a HP.
I have a flat where a boiler change is long overdue - but I can't find an installer who can be bothered to actually work out something that's both possible and regs compliant. Given it already has a thermal store, a HP is starting to look tempting apart from the impact it would have on the EPC (currently D by one point, and I have a cheap and easy route to gain that one point to make it C).

 

[transam]

We are indirectly involved in a large prop that has lake source heat pumps

Cost in excess of 250 grand

3 phase leccy brought in

Running costs are a financial black hole

If it runs on full pelt ?? And you add up all the equipment it’s some thing like 120 kw/ hr ( leccy) system is total
S**te imho

Put an ASHP in my mates new build 10 / 12 years ago

All under floor heating

Hot water and towel rails via a combi

 

[transam]

Afaik that fruit cake Milliband is going to introduce or reintroduce a gas boiler tax

 

[diy_fun_uk]

Afaik that fruit cake Milliband is going to introduce or reintroduce a gas boiler tax

He's like a dog with a bone, prob wants the green stuff to be his political legacy, as opposed to this ...