Ground Source heat pump advice

[ProDave]

I'm first fixing a new build heated by a ground source heat pump and (wet) under floor heating.

I have the data for the UFH but the builder has no info at all on the ground source heat pump.

So how do I first fix it?

Here's what I have dome:

6mm t&e power feed (I've heard they can consume a lot of power)

2.5mm t&e mains feed to UFH controller together with all thermostats fed back to the UFH controller.

It's how to join the UFH to the heat pump I don't know.

Do they work like a conventional boiler? i.e does it just need power and "call for heat"?

The time clock will be next to the UFH controller.

So I've installed FOUR 1mm 3 core & e cables between the UFH controller and the ground source heat pump. Surely that will be enough (pump, call for heat and 2 spares was my thinking)

As well as being electricians, we have to also guess the requirements.

 

[steptoe]

careful Dave, some of them need shielded cable for the ELV controls, a couple I have done used 2pair beldon cable.

last one I done required a 32A feed and a 10A feed, plus 12 interlinks to the wiring centre, as well as the 2pair beldon to the control panel,

I dont have any schematics for ground-source, but I have one for an Air Source if you want to have a look, they are normally pretty similar to what is needed.

 

[ProDave]

Thanks Steps.

So I'll have to impress on the builder NOT to plasterboard the utility room until he can give me all the information.

Otherwise it will all be surface wiring in trunking.

Looks like a 2.5 power feed as well as the 6mm just in case

I guess if the controller goes on the wall above the heat pump, then any special cables can be fished through the service void behind the plasterboard. At this stage I just want to ensure enough interconnections from UFH to the heat pump

 

[Sparkystu79]

The last ground source heat pump I installed required a 50Amp supply and a permanent supply to the wiring centre where each actuator for the zones was connected via room stats. There was no programmer, only an internal sensor, external sensor and cylinder sensor. The system ran all the time and regulated the temperature based on the temp at each sensor.

 

[batty]

He really needs to get the info before he goes too far. All the ones I have done have had different requirements thats not to say I have done a lot but the ones I have done have been different.

 

[ProDave]

Okay I'm back second fixing this one now. Yes I know, a very slow build, I think the builder is doing this as a fill in job so does bits and pieces as and when.

So finally I have seen the ground source heat pump. The instructions are about as useful as a chocolate tea pot.

It gives a table of input current ratings, but you have to look up which power variant it is. Max input currents range from 20A to 59A depending on the model. And guess what? I can't see anything on it to say what model variant it is, and I couldn't take the cover off as it needs a torx screwdriver bit and all my security bits were at home. So that will have to wait for another day to find out it's actual rating. It comes with a length of 10mm sq 3 core flex attached.

As to other controls, there's precious little in the manual, I'm hoping it becomes clear when I open it up.

Due to the fact I couldn't get the cover off, I spent most of the day wiring the CU and starting on the UFH so the joys of the heat pump will wait for another day when I can get the cover off.

One thing I have noticed is it has an external outside temperature probe that must be mounted on the north facing wall. Oh how I wish I had known that when first fixing. The heat pump is adjacent to the south facing wall. It's too late to run cables inside the house, so all I can think is a bit of SWA buried around the perimeter of the house.

As for the UFH it's the most rubbish controller I have ever seen. Just an awkward fiddly thing to wire with not enough earth or L and N terminals for the amount of cables that you need. Oh and the builder has supplied a single channel programmer so I'm waiting to ask him just exactly how he wants the hot water configured as there's no timer channel for that.

And as well as the ground source heat pump there's a pressurised hot water tank (makes sense) but also another big square box that has pipe fittings but no wires, so I guess that's another tank. I can't wait to see the pipework and all the controls I need to figure out for this one.

Still you can't accuse this of being a simple, uninteresting job.

 

[LNRDF01]

you should really get the information from the manufacturers and you also have to work out the space heating for each room, are you MCS registered or is the Builder

 

[ProDave]

No I'm not MCS registered? What relevance is that?

Space heating is wet UFH downstairs and radiators upstairs.

I have the installation manuals but they are next to useless. I guess a phone call may be needed if it does not all become clear when I remember the correct tool to undo the bloody screws.

 

[Steve3948]

Dave, I did a couple of Ground Source Heat Pumps last year, they were in parallel, with 6KW Heating Element in each for back-up should the ground source not be good enough. The sales guy told the client the electric elements would hardly be used and then only in extreme cold weather, however that was not the case and I believe the client has never been 100% happy.

We ran 2 x 6.0mm

 

[ProDave]

Thanks Steve

Yes I understand a lot of UFH systems run 24/7, often with a temperature set back overnight.

Are you saying that your system, the GSHP ran 24/7 as well? or did it just come on when the storage cylinder called for heat?

If the storage tank is kept topped up all the time, surely there's no need to turn the hot water on or off?

I need to speak to the plumber (who has never been in site the same time as me yet) to understand how it's supposed to work.

 

[Steve3948]

Thanks SteveYes I understand a lot of UFH systems run 24/7, often with a temperature set back overnight.

Are you saying that your system, the GSHP ran 24/7 as well? or did it just come on when the storage cylinder called for heat?

If the storage tank is kept topped up all the time, surely there's no need to turn the hot water on or off?

I need to speak to the plumber (who has never been in site the same time as me yet) to understand how it's supposed to work.

Yes the GSHP's were 24/7 and had a couple of fancy optimizer control panels on the front of each although the Master controlled the Slave and they constantly monitor temps in storage vessel, outdoor stat temp, indoor stat temp (nothing to do with ufh stats), flow pipe stat.

From what I gathered the storage vessel was maintained at a constant set temperature at all times.

---------- Post Auto-Merged at 21:09 ---------- Previous post was made at 21:05 ----------

Yes the GSHP's were 24/7 and had a couple of fancy optimizer control panels on the front of each although the Master controlled the Slave and they constantly monitor temps in storage vessel, outdoor stat temp, indoor stat temp (nothing to do with ufh stats), flow pipe stat.From what I gathered the storage vessel was maintained at a constant set temperature at all times.

The Hot Water control was a client request, as they are not there until weekends, so just wanted the Hot Water weekends and felt it was energy that could be used on the ufh in the week.

 

[steptoe]

Dave, from the two cylinders there should be enough internal coils for the radiators to draw from,

the hot water is on 24/7 and it is the tank temperature that fires the GSHP, remember, the radiators will be getting their feed from the same tank,

the programmer will be to tell the radiators[sorry, UFH] when to call for heat,[depending on stat settings of course].

short version, hot water is on constant, controlled by tank stat, programmer controls UFH.

---------- Post Auto-Merged at 21:18 ---------- Previous post was made at 21:12 ----------

Okay I'm back second fixing this one now. Yes I know, a very slow build, I think the builder is doing this as a fill in job so does bits and pieces as and when.So finally I have seen the ground source heat pump. The instructions are about as useful as a chocolate tea pot.

It gives a table of input current ratings, but you have to look up which power variant it is. Max input currents range from 20A to 59A depending on the model. And guess what? I can't see anything on it to say what model variant it is, and I couldn't take the cover off as it needs a torx screwdriver bit and all my security bits were at home. So that will have to wait for another day to find out it's actual rating. It comes with a length of 10mm sq 3 core flex attached.

As to other controls, there's precious little in the manual, I'm hoping it becomes clear when I open it up.

Due to the fact I couldn't get the cover off, I spent most of the day wiring the CU and starting on the UFH so the joys of the heat pump will wait for another day when I can get the cover off.

One thing I have noticed is it has an external outside temperature probe that must be mounted on the north facing wall. Oh how I wish I had known that when first fixing. The heat pump is adjacent to the south facing wall. It's too late to run cables inside the house, so all I can think is a bit of SWA buried around the perimeter of the house.

As for the UFH it's the most rubbish controller I have ever seen. Just an awkward fiddly thing to wire with not enough earth or L and N terminals for the amount of cables that you need. Oh and the builder has supplied a single channel programmer so I'm waiting to ask him just exactly how he wants the hot water configured as there's no timer channel for that.

And as well as the ground source heat pump there's a pressurised hot water tank (makes sense) but also another big square box that has pipe fittings but no wires, so I guess that's another tank. I can't wait to see the pipework and all the controls I need to figure out for this one.

Still you can't accuse this of being a simple, uninteresting job.

Dave, I done an ASHP in that there London village, it was an afterthought as well! and was on a south facing wall, on speaking to the manufacturer they were happy enough to have the external stat on the same wall, as long as it was shaded and a couple of metres away, not ideal, but the best we could do as the client didnt want anything round the building, and all paths etc had been laid,

AFAIAA the manufacturer changed some of the parameters of the system to allow for the stat being in this position,

I think there may be pix somewhere on here.

do you know the make of your system?

 

[ProDave]

Thanks Steps.

It's all starting to make sense. I think what really winds me up is the instructions just say connect it like this and turn it on. but I like to understand HOW it is supposed to work and what it's doing.

I'll talk to the builder re the outside stat. The ground work on the site has not been done yet, so digging a trench round for SWA may not be an issue. They will have to get a digger on site soon to lay the drains, dig the trenches for the incoming services and landscape the site, so digging an extra trench for a bit of SWA round to the north side of the building ought to be trivial in the scale of things. It can't be done right now as the scaffold is still up as the guy is still doing the harling (rendering for you south of the border) but I should be able to lay in the SWA with enough slack to drop into the trench once it has been dug.

 

[SLIPSHOD & SLAPDASH]

We worked on a super Eco friendly house a few years back with every gizmo available. The owners have just asked our opinion as after some research they worked out 62% of the total power consumption of the house is the ground source heat pumps & they may be better off not using them.

 

[steptoe]

how deep/long is the pipe?

thats where all the money is in installing GS

 

[ProDave]

No idea Steps, I wasn't there at the ground work stage.

All I know is there are two loops of pipe underground that then tee together into the GSHP.

---------- Post Auto-Merged at 08:46 ---------- Previous post was made at 08:22 ----------

We worked on a super Eco friendly house a few years back with every gizmo available. The owners have just asked our opinion as after some research they worked out 62% of the total power consumption of the house is the ground source heat pumps & they may be better off not using them.

Agreed that does seem rather high. Reading the instructions, it seems the high power load is an immersion heater to cope with periods when there's insufficient heat from the ground source.

If it were mine, I would want to fit a monitor to measure how often that immersion heater was coming on, i.e to see how much of the heat was really from the ground source.

 

[binky]

We worked on a super Eco friendly house a few years back with every gizmo available. The owners have just asked our opinion as after some research they worked out 62% of the total power consumption of the house is the ground source heat pumps & they may be better off not using them.

Anything that relies on electric is going to be expensive to run, even if you are getting 5-1 ratio that's still 1kw leccy for 5 kw from system.

 

[ProDave]

Renewable Heat Incentive / Funding and finance / Professional resources / Home (United Kingdom) - Energy Saving TrustIts like the Feed In Tariff for Solar PV and WInd - Called RHI

By the way, what you have described roughly sounds like a pile of carp that will be expensive to run......

Interesting stuff. I didn't know that.

However this house is being build by a developer for sale. Reading through that lot I found "Please note applications from installers, builder/developers or householders in relation to “off-plan” developments, are not eligible for support under this scheme"

So I guess he doesn't qualify, but perhaps whoever buys the house might.

Will they ever start paying me to burn wood in my wood burning stove I wonder?

 

[SLIPSHOD & SLAPDASH]

In our case the house had everything, PV tiles, wind generator and 3 Ground pumps, one under the York stone drive, one under the lawn & one in the lake. The house had a 3 phase battery room bigger than my bathroom. The owner reckoned he could go off line for 3 months

 

[steptoe]

In our case the house had everything, PV tiles, wind generator and 3 Ground pumps, one under the York stone drive, one under the lawn & one in the lake. The house had a 3 phase battery room bigger than my bathroom. The owner reckoned he could go off line for 3 months

did you hear about the lake that froze cos there was so many people running GSHPs out of it?

I dont think it actually 'froze' but it was very close to it, killed all the fish.!