[PeterL[_2_]]

Does anyone have any views or experience, please? Good or bad.

[The Natural Philosopher[_2_]]

PeterL wrote:
Does anyone have any views or experience, please? Good or bad.


Views and research yes, experience no.

Because the costings indicated it wasn't worth it yet. In my case.

Some things I learnt. (ground source only)

1/. For a decent output, you need a pretty big garden. Ok here.

2/. For a decent output, you need a pretty big pump. Enough to strain a
single phase..three phase better.

3/. Its best delivering a lot of warm water: efficiency is poor at
delivering hot water.

4/. Because of that, you need a lot of radiator or UFH.

5/. Because of that you need rather larger pipes in your CH circuits.

6/. Because of that you need rather more coil in the tank heat exchanger
for hot water.

7/. Because of that you need a supplementary imersion heater to get teh
water up to say 55 or 60C to make it sterile and safe in hot wate circuits,.

Bceause of 4,5 and 6, I was facing a complete replumb: hat pushed teh
cost upp to about £20k.

IF I had been green fielding, I would actually have done it though. It
should be fuel cost competitive with oil at 30p a liter.


However, with oil costs at £2500 a year these days, I might save £1000 a
year BUT the installation looked like about 20 grand with all the mods.

I may live beyond 20 years, but probably not here..

[Adrian Brentnall]

On 02/02/2011 12:19, PeterL wrote:
Does anyone have any views or experience, please? Good or bad.


HI Peter
We have a ground-source heat-pump installation here (far south-west of
Ireland)
Total install costs were c. 12k euro - but there was a subsidy available
(c. 4k euro) at the time.

Our heat-pump lives outside in the timber-built studio - and draws heat
from 6 x 100m loops, set in three 50m trenches, partly under the
polytunnel. The ground-work is a significant part of the install costs -
in our cease we had to do some earth-moving anyway - so buried the loops
at the same time.

Our pump is designed to replace a conventional boiler (original install
was an oil-fired unit) - and circulates water at about 55 - 60c to
radiators. If designing from scratch, you'd want larger rads or
underfloor pipework.

Had to replace the hot-water cylinder with one that had a larger, longer
coil, as otherwise the heat-pump got upset at the reduced heat-loss..

We like to have 2 baths one-after-the-other of an evening - and find
that there's a tiny amount of mains immersion heater needed just to top
off the tank and achieve this. If the DHW tank was a little larger then
this wouldn't be a problem.

Can't comment on actual cost of operation - but I believe it to be
cheaper than oil, more convenient and less smelly! g

Servicing costs - so far (fingers crossed) - zero in 3 years.
Electric supply needs to be sized carefully - unit takes 15A when
running - but has a fairly high inrush on starting (32A slow-trip MCB
required).

Hope this helps.
Adrian

[harry]

On Feb 2, 12:19*pm, "PeterL" wrote:
Does anyone have any views or experience, please? *Good or bad.

Air source work less well when you need them, ie as the air outside
gets colder. You would need an auxilliary source of heat cold weather.
Obviously they are much cheaper to install.
Subject to the above they are much cheaper than storage heaters to
run.
Both sorts can be reversible, ie they can cool the place. When there
were grants, this option was not allowed.
You need to do your sums before deciding which to go for.

[Andrew Gabriel]

In article ,
harry writes:
On Feb 2, 12:19*pm, "PeterL" wrote:
Does anyone have any views or experience, please? *Good or bad.
Air source work less well when you need them, ie as the air outside
gets colder. You would need an auxilliary source of heat cold weather.

I installed mine (which is part of an aircon unit) about 5 years ago.
I discovered that they don't work well when the outside coils drop to
zero, as they ice up, or would do if the unit didn't keep defrosting
them, which causes it's efficiency to plummet. This happens below
about 5C.

Then when we had a really cold spell and it was more like -5C outside,
I tried it and found it worked fine, without doing defrost cycles.
So there's a window from something like -2C outside to +5C outside
where it's inefficient due to defrost cycling (blowing large clouds
of fog across the back garden), but above and below this window, it
works fine. I don't know what the absolute lowest it works at is,
as I've not tried experimenting.

Obviously they are much cheaper to install.
Subject to the above they are much cheaper than storage heaters to
run.
Both sorts can be reversible, ie they can cool the place. When there
were grants, this option was not allowed.

Aircon units which can heat too are only subject to 5% VAT if the
seller can be bothered to do the paperwork. However, I found that
one which didn't bother with that and had a special offer was cheaper
overall than one which did.

I use mine for probably 96% heating and 4% cooling. It's mainly used
to heat my work room when I'm working at home, so I don't have to
heat the whole house.

You need to do your sums before deciding which to go for.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

[Jules Richardson]

On Wed, 02 Feb 2011 17:42:35 +0000, Andrew Gabriel wrote:
Then when we had a really cold spell and it was more like -5C outside, I
tried it and found it worked fine, without doing defrost cycles. So
there's a window from something like -2C outside to +5C outside where
it's inefficient due to defrost cycling (blowing large clouds of fog
across the back garden), but above and below this window, it works fine.
I don't know what the absolute lowest it works at is, as I've not tried
experimenting.

I think they're generally thought to stop working at around -20C (which
renders them useless where I am; it was a nipply -34C this morning)

cheers

Jules

[PeterL[_2_]]

Thank you, to everyone that replied. Some very good information there.

[Ian Stirling[_3_]]

PeterL wrote:
Does anyone have any views or experience, please? Good or bad.

A contrary view.
For the money you will spend on a ground source heatpump, you can
often vastly improve the thermal efficiency of the building
instead.

10K may go a long way to properly insulating a solid wall
property, for example.

This means that in 10 years, you don't need to spend another
5-10K replacing the heatpump.

In some cases, combined with storage heaters, the running costs
can be drastically cheaper than with a ground or air source
heatpump.

Another fun thing to think about is a teeny groundsource
heatpump that uses cheap-rate electricity to heat a thermal
store for a well insulated property.

[The Natural Philosopher[_2_]]

Ian Stirling wrote:
PeterL wrote:
Does anyone have any views or experience, please? Good or bad.

A contrary view.
For the money you will spend on a ground source heatpump, you can
often vastly improve the thermal efficiency of the building
instead.

10K may go a long way to properly insulating a solid wall
property, for example.

Very true. BUT we assume that's already been done.


This means that in 10 years, you don't need to spend another
5-10K replacing the heatpump.


Heatpump itself not expensive. Its the rest...

In some cases, combined with storage heaters, the running costs
can be drastically cheaper than with a ground or air source
heatpump.

Another fun thing to think about is a teeny groundsource
heatpump that uses cheap-rate electricity to heat a thermal
store for a well insulated property.

You would still be surprised..how much heat that takes.

It IS now cheaper to heat with a heatpump, running cost wise, no matter
what the level: the problem is the installation and ancillary costs for
houses simply not designed for it, are very large.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Jules Richardson
saying something like:

it was a nipply -34C this morning

Yes, that would stand out a bit.

[GB]

The Natural Philosopher wrote:

6/. Because of that you need rather more coil in the tank heat
exchanger for hot water.

7/. Because of that you need a supplementary imersion heater to get
teh water up to say 55 or 60C to make it sterile and safe in hot wate
circuits,.

If the water from the heat pump is cooler than the water temperature in your
cylinder, aren't you going to end up heating the house from the immersion
heater?

[The Natural Philosopher[_2_]]

GB wrote:
The Natural Philosopher wrote:
6/. Because of that you need rather more coil in the tank heat
exchanger for hot water.

7/. Because of that you need a supplementary imersion heater to get
teh water up to say 55 or 60C to make it sterile and safe in hot wate
circuits,.

If the water from the heat pump is cooler than the water temperature in your
cylinder, aren't you going to end up heating the house from the immersion
heater?



Gosh. You would have thought that people had heard of motorised valves
and separate circuits.

And timers.

[Ian Stirling[_3_]]

The Natural Philosopher wrote:
Ian Stirling wrote:
PeterL wrote:
Does anyone have any views or experience, please? Good or bad.

A contrary view.
For the money you will spend on a ground source heatpump, you can
often vastly improve the thermal efficiency of the building
instead.

10K may go a long way to properly insulating a solid wall
property, for example.

Very true. BUT we assume that's already been done.

I've quite often seen it unfortunately not done.

This means that in 10 years, you don't need to spend another
5-10K replacing the heatpump.

Heatpump itself not expensive. Its the rest...

Can you point me at a source of inexpensive heatpumps?
I have singularly failed to find them.

In some cases, combined with storage heaters, the running costs
can be drastically cheaper than with a ground or air source
heatpump.

Another fun thing to think about is a teeny groundsource
heatpump that uses cheap-rate electricity to heat a thermal
store for a well insulated property.

You would still be surprised..how much heat that takes.

Teeny, compared to the uninsulated state, I mean.

For this house, at the moment, at 20C over ambient - 7.1Kw.
(calculated - it's pretty close to this in reality).

Once I've got the insulation upgrades in, it's around 1.5Kw.
(depending on stuff, I'm pondering on getting it to 1Kw, but that's
probably in the diminishing returns range)

A 4.5Kw(th) heatpump, running into a thermal store off
night-rate electricity could in principle do the heating for
very little continual outlay.

It IS now cheaper to heat with a heatpump, running cost wise, no matter
what the level: the problem is the installation and ancillary costs for
houses simply not designed for it, are very large.

Of course.
If you've done the insulation to the best standard.

If you're not, then you can run into the scenario above - when the
heatpump will take you back to the same power usage (more or less)
as a properly insulated property.

Of course, comparing prices of heating with electricity, a heatpump
looks a hell of a lot less of a bargain if you can heat with gas,
or even a good night-rate storage based system.

If you have mains gas, your house is not properly insulated, then
putting in a heatpump would be a very questionable decision indeed.
(from a cost point of view, I can see it might be nice if you want
to keep a 'historic' structure, and

[Ian Stirling[_3_]]

GB wrote:
The Natural Philosopher wrote:

6/. Because of that you need rather more coil in the tank heat
exchanger for hot water.

7/. Because of that you need a supplementary imersion heater to get
teh water up to say 55 or 60C to make it sterile and safe in hot wate
circuits,.

If the water from the heat pump is cooler than the water temperature in your
cylinder, aren't you going to end up heating the house from the immersion
heater?

I did that when my CH boiler died.

Needless to say, the element failed in fairly short order.