Ground Source Heatpump Problems

GSHP_Problems

Could anybody offer some advice about ground source heatpumps please? I'm finding the system more expensive to run than my neighbours in bigger houses with oil or lpg boilers.

I had a ground source heatpump system installed in Feb 09. The manufacturer actually installed the system and specified that no controls were to be fitted. As a result, there are no internal temperature controls/timers, no trv's on the radiators and the underfloor area had to be controlled as one zone (the extension has three bedrooms and two bathrooms). Radiators are oversized and I had to install a temperature sensor in the underfloor area to stop it from becoming a sauna.



I'm having a lot of headaches with the system:

• The internal temperature of the house has varied by up to 4 degrees in the radiator area
• Exceptionally high energy consumption, 1700kw/h in the last 5 weeks. Prior to sale, the manufacturer stated that it would cost £78 to run in a hard winter month but the reality is almost double.
• Five breakdowns in 12 months

I have had lots of costly 'advice' from the manufacturer, the latest being installation of a buffer tank which has actually increased energy consumption.
Does anybody have any ideas on how I might improve efficiency and operation? I am rapidly coming to the conclusion that I shouldn't have been advised to install the system.

albyota

Surely you should be getting the manufacturers/installers back in to explain why no controls were specified and they should be putting things right, at their expense, if they want to maintain their reputation (if they have a good one that is), I would be having a field day on this, as I would expect our customers to if we fitted a system that did not deliver.
The problem with GSHP is, if it is not designed correctly and largely over engineered then problems will always arise. did you have boreholes or slinkies? was a proper geotechnical assessment carried out? if the ground temperature cannot recover fast enough.....a bank of immersion heaters provide the very expensive backup. With any heating system, controls are the most important feature, so I can only agree that you were ill advised by this company. not sure whether you are allowed to name and shame the company? this is a moneysaving forum and you are clearly not saving any with that set-up.

Andy_WSM

No controls = excessive heat where it isn't needed = wasted energy.

The bedrooms should have been zoned IMO, so you could avoid heating them in the day and only heat them first thing in the morning, last thing in the evening, for example.

The underfloor heating should never have run hot enough to be "like a sauna". Sounds like a very badly designed system to me.

I agree with albyota that the manufacturer should be putting this right.

lomb

One option may be to remove it and install a conventional oil or gas boiler. GSHPs are a tech geeks dream but arent ready for the big time as they like underfloor heating need to be expertly designed and installed with numerous controls which means that it is technique (very) sensitive( and expensive) which therefore means that in many cases a disaster awaits. Also something to take into account is if say in the unlikely event a worcester boiler fails then one can get a next day fixed price callout something that isnt possible with heat pumps be they ASHP or GS. When you think about it a 24kw boiler can be had for 500-800 quid something that heat pumps cannot compete with.

albyota

lomb wrote: »

One option may be to remove it and install a conventional oil or gas boiler. GSHPs are a tech geeks dream but arent ready for the big time as they like underfloor heating need to be expertly designed and installed with numerous controls which means that it is technique (very) sensitive( and expensive) which therefore means that in many cases a disaster awaits. Also something to take into account is if say in the unlikely event a worcester boiler fails then one can get a next day fixed price callout something that isnt possible with heat pumps be they ASHP or GS. When you think about it a 24kw boiler can be had for 500-800 quid something that heat pumps cannot compete with.

There is a bit of a difference between a system that has been incorrectly designed and installed, to many good installations.
Heating water is not rocket science....whether it be ASHP or GSHP and when used with underfloor heating it is very easy to design and install.

Controls should be fitted to any system...there is no difference whether ASHP, GSHP, Gas, LPG or Oil...they should all be fitted with time clocks, programmers, room sensors/night set back thermostats and motorized zone valves...that is what makes any heating system efficient.

The bit that many seem to get wrong with GSHP, is calculating the amount of boreholes...slinkies....depth and size of heat pump...flow rate....and most importantly...and nothing anyone can do about.... is last years iradiation from the sun to warm the ground, and the recovery rate of the sub-soil. This is where ASHP's are better...cheaper to install and much more controllable...we know exactly what the air temperatures are!!

Wacking an oil or lpg boiler in is great.... much cheaper to buy and replace. it will work whatever the ambient temperature (below minus 20), but has its own issues, with it being smelly, having to store enough for the winter, (Contract/ Rental) risk of running out, the annual service charge and the rising cost.

A bad / incorrectly designed installation of any type of heating system can be a disaster waiting to happen.

lomb

albyota wrote: »

A bad / incorrectly designed installation of any type of heating system can be a disaster waiting to happen.

The difference is there are many 'bad' installations of traditional systems. The house I live in was built in 1990 and although well insulated has no motorized valves ,a retrofitted condensing gas boiler(originally oil ), retrofitted trvs(originally none) and what irks me most is to heat the water one can use gas but as its on the radiator circuit means that when the heating isnt needed one has to use the immersion .It could do with a seperate circuit to the boiler and a motorized valve but that means running pipes outside and cutting the concrete and my pay back calculations mean it is not worthwhile. Also there is no house thermostat and only a time clock/on off for the boiler. Saying all the above it is not a bad system, heats the house from cold in 20 minutes and there is unlimited hot albeit expensive water didnt cost alot originally to install or maintain subsequently. I wonder if someone had under floor heating or a GSHP installed and the installation was guntered would the same be said? I doubt it.

lomb

Ps ive gone for ASHP/air conditioning units in my new business premises and these should be running within a week and I shall report back on these versus conventional radiators.

albyota

I actually have an ASHP with underfloor heating, fitted by me, no problem heating the house to 23 degrees even at minus 10, loads of low cost hot water, seperate room controls. (nothing technical about it) It was not that costly to install over a traditional oil and rads/TRV's installation. but the point is, I now have the lowest bills ever!!.

"I wonder if someone had under floor heating or a GSHP installed and the installation was guntered would the same be said? I doubt it."

What I think the OP was actually saying was exactly that....! the system works... but is expensive...(Mainly due to lack of controls) although the last 12 weeks does account for some of the coldest temperatures in 30 years and so to get any house comfortable will use more energy......these threads are full of comments from high usage bills.

albyota

lomb wrote: »

Ps ive gone for ASHP/air conditioning units in my new business premises and these should be running within a week and I shall report back on these versus conventional radiators.

Glad to here you are doing the right thing, you should be very happy with it.
What make have you opted for?

lomb

How does one go about installing controls in a new build or refurb? Most plumbers ive met see the limit of controllability as some trvs. Where does one find the specs for motorized valves, wiring diagrams, room thermostat wiring seperate valves for hot water etc etc, and where are all these valves fitted, in the boiler house? So all pipes for a circuit are led back to the boiler house with wiring for multi room thermostats? Sounds like a grand designs project to me.

albyota

lomb wrote: »

How does one go about installing controls in a new build or refurb? Most plumbers ive met see the limit of controllability as some trvs. Where does one find the specs for motorized valves, wiring diagrams, room thermostat wiring seperate valves for hot water etc etc, and where are all these valves fitted, in the boiler house? So all pipes for a circuit are led back to the boiler house with wiring for multi room thermostats? Sounds like a grand designs project to me.

Zoning a system can be as simple as re-configuring the pipe work and fitting a motorised valve to the upstairs radiator circuit on a seperate programmer channel, (There are remote control TRV's on the market now)Honeywell http://www.honeywelluk.com/ have a good site for downloading tech specs PDF's for motorised valves, and controls as do Danfoss http://danfoss-randall.co.uk/Content/ECE3CA00-298C-4305-9D87-B44ED1C71699_MNU17434508_SIT313.html

nothing 'grand designs' about it ...it is normal practice in my industry.