Geothermal Heating

Larsheen

Hi,
I am hoping for some advice/guidance.I am in the early days of house hunting and am looking at a house which has, according to the sales blurb, geothermal (bore hole system)under floor heating and hot water system.It is a bungalow, 7 rooms, about 1500 sq feet overall with option to convert attic.I think it is about 10 yrs built.What sort of questions should I be asking in order to establish that the heating system is fit for purpose system? What sort of Kw should the system be? Thank you in advance for any info or guidance you can give.

Calahonda52

might fly better over in Renewables

Metric Tensor

Top of the list if you can get them is the last year of ESB bills. You'll know pretty quickly from these how efficiently the system is operating.

Then ask when the heat pump was last serviced and request a copy of the dated service documentation.

Ask for make and model of system too and look up the advertised "coefficient of performance" but the electricity bills will tell you a LOT more.

Larsheen

Metric Tensor wrote: »

Top of the list if you can get them is the last year of ESB bills. You'll know pretty quickly from these how efficiently the system is operating.

Then ask when the heat pump was last serviced and request a copy of the dated service documentation.

Ask for make and model of system too and look up the advertised "coefficient of performance" but the electricity bills will tell you a LOT more.

Thank you.I know there are lots of variables and influences but would you have any rough idea of what sort of money the ESB bills should be coming in at?I gather there are just two people living in the house so there would be no huge uses of showers from teenagers etc.Or does that matter with geothermal?

Metric Tensor

With geothermal and associated underfloor they will most likely keep the whole house at a relatively stable temperature so the central heating load will probably be fairly indicative regardless - unless they live in the cold!

All heat pumps are inefficient at producing hot water because they are only efficient at heating water to 30-40 degrees rather than the 60 in you HW cylinder. You can take it that it's slightly more efficient than using an electric immersion for HW.

Calahonda52

As above +
I would ask to see the spec on the bore hole: is it a single hole or a two hole system?
what depth is it and what is the effort required by the pump: i.e. the net lift?
How deep is the hole and what age is the pump?
How hard is the water => if limey/hard then limescale on the heat exchanger will drive down efficiency

Larsheen

Thank you all.Our last 3 bi monthly combined Gas and ESB bills were 265,235 and 270 Euros.I appreciate there should be no gas bills with Geothermal and that houses vary in all sorts of ways but should the ESB bills for a house with a B3 rating be in and around those figures or lower.I suppose I am trying to determine what the bills should look like if I get a look at them.The house is ideal but having asked for a make of system and kilowatts from the estate agent three days ago with no reply my suspicions are raised.Especially when he was very quick to return calls before.Thanks again

Metric Tensor

What I'm not so subtly hinting at is that if the geothermal system is poor (or poorly managed to be fair) or inefficient the annual electricity usage will be substantially higher than your combined gas an electric usage - but you need to look at annual usage to account for winter and the possibility of "level pay" options.

Unfortunately, unless you personally know the owner, I'd say there is zero chance you'll get them.

The bills show in use efficiency of the house versus the theoretical asset rating of the BER. The upside of bills is you get a good indicator of underperformance but the downside is that it's dependant on the owner's usage vs the BER which compares houses on a relatively like for like usage but using theoretical efficiency figures from the manufacturers.

The first thing you are looking for is crazy high electricity bills to identify problems and further to see how much it will cost to run. And the second thing is age and maintenance issues so you know the ongoing maintenance/replacement costs.

Larsheen

Metric Tensor wrote: »

What I'm not so subtly hinting at is that if the geothermal system is poor (or poorly managed to be fair) or inefficient the annual electricity usage will be substantially higher than your combined gas an electric usage - but you need to look at annual usage to account for winter and the possibility of "level pay" options.

Unfortunately, unless you personally know the owner, I'd say there is zero chance you'll get them.

The bills show in use efficiency of the house versus the theoretical asset rating of the BER. The upside of bills is you get a good indicator of underperformance but the downside is that it's dependant on the owner's usage vs the BER which compares houses on a relatively like for like usage but using theoretical efficiency figures from the manufacturers.

The first thing you are looking for is crazy high electricity bills to identify problems and further to see how much it will cost to run. And the second thing is age and maintenance issues so you know the ongoing maintenance/replacement costs.

Thank you again Metric Tensor.I suspect that you are correct and that the bills won't be forthcoming based on the agent's seemingly reluctance to provide details of make, model and kilowatts as requested.I must say that we got the 'wrap around' insulating done a few years ago and our bills dropped by over half straight away and if we are asked by potential purchasers of this house to show them proof the insulating has worked,I'd be only too delighted to.The house we're looking at was a new build, around 2008 so I think it is probably fair to conclude that the heating system was installed at the time of build.The very least I'd want to be seeing is a service record because if the Geothermal is not up to scratch I don't want to be facing the associated bills to fix or replace it, and as you have advised the service record would be just a bare comfort. I will thread carefully on this but suspect already that we might have to walk away.The house would be our retirement, it's a three hours drive away,so this makes the whole process more challenging and I just don't need to be facing the added grief at this stage of my life.Thanks again for your help

Metric Tensor

A couple of things I should also point out to be fair:

A properly designed, installed and maintained geothermal system can be very efficient when heating an appropriately specified house.

Also - worst case scenario, it would probably be possible to replace the geothermal heat pump with an air to water one of you had to install a new heat pump and the upfront costs of the geothermal were prohibitive.

Czhornet

Make sure there is a night rate meter in the meter box, run your heating at night its the cheapest option

Larsheen

Metric Tensor wrote: »

A couple of things I should also point out to be fair:

A properly designed, installed and maintained geothermal system can be very efficient when heating an appropriately specified house.

Also - worst case scenario, it would probably be possible to replace the geothermal heat pump with an air to water one of you had to install a new heat pump and the upfront costs of the geothermal were prohibitive.

I suppose it’s chicken and egg in that I wouldn’t know whether the system has been all those things until I’d get the relevant info *prior* to sale agreed etc. Similarly if it seemed like the system needed to be upgraded or replaced with an air to water one then we’d need to be allowing for that in the finances. Either of the price paid for the house or future spend. So again it would be important to have more info as you mentioned earlier.The house is on the north west coast, 45 mins from a town of substance and the normal logistics of getting a gas/oil boiler serviced would surely be added to if it is a Geothermal one!

Czhornet

Larsheen wrote: »

I suppose it’s chicken and egg in that I wouldn’t know whether the system has been all those things until I’d get the relevant info *prior* to sale agreed etc. Similarly if it seemed like the system needed to be upgraded or replaced with an air to water one then we’d need to be allowing for that in the finances. Either of the price paid for the house or future spend. So again it would be important to have more info as you mentioned earlier.The house is on the north west coast, 45 mins from a town of substance and the normal logistics of getting a gas/oil boiler serviced would surely be added to if it is a Geothermal one!

There is actually a good lad up that side of the country that services geothermal pumps. PM me for details if needed