Ground Source Heat Pumps

Xander_Sim

Silent_Dancer wrote: »

I have weather comp on a gas boiler. Apart from adjusting the bottom end of the heat curve up to -3°C to suit UK heating design parameters. I have had to do nothing to it.

The issue is not weather compensation it is to do with the fundamentals of running a low temperature heating system. With low flow temperatures you can not respond quickly to changes in demand either due to the weather or from the occupants. The theory behind heat pumps is fine but the reality is different.

My GSHP had +6 to deal with yesterday and -4 today, lovely and warm in here today, exactly the same as it was yesterday. There are no compromises with GSHP, they are the thing of present and future.
For new builds especially with good suitable ground to use, let's just say I'd put exactly the same in again if I had the choice.

Xander

beardymarrow

Xander_Sim wrote: »

My GSHP had +6 to deal with yesterday and -4 today, lovely and warm in here today, exactly the same as it was yesterday. There are no compromises with GSHP, they are the thing of present and future.
For new builds especially with good suitable ground to use, let's just say I'd put exactly the same in again if I had the choice.

Xander

Same here. GSHP has maintained the house temp to 0.1degC 24 hours a day for the last 4 days (since I last made any changes to it :-) ). My old gas central heating at the old house wasn't that stable by any means (wasn't weather compensated though).

beardymarrow

Silent_Dancer wrote: »

I have weather comp on a gas boiler. Apart from adjusting the bottom end of the heat curve up to -3°C to suit UK heating design parameters. I have had to do nothing to it.

The issue is not weather compensation it is to do with the fundamentals of running a low temperature heating system. With low flow temperatures you can not respond quickly to changes in demand either due to the weather or from the occupants. The theory behind heat pumps is fine but the reality is different.

Whatever heating system you have, you have 3 different temperatures of water to deal with (DHW, Rads and UFH), so the system you have it has to cope with that. IMHO GSHP does a fantastic job of providing all 3 (if there's a mixer valve fitted for the UFH).

beardymarrow

Patrol wrote: »

So if I understand correctly a GSHP, UFH & radiators with no mixer valve or buffer tank is not ideal;
- The heating circuit will run at circa 35c, ideal for UFH but not optimal for radiators even if oversized (Long response time, costs and potentially never reaches desired temperature).
- The GSHP will cycle more than necessary as the small quantity of water in the heating circuit cools rapidly as it does it's job of transferring heat to the property (Increased wear & running costs).

Adding a buffer tank and mixer valve allows a store of water at a higher temperature (in the 40's?). Benefits;
- Radiators run closer to their optimal temperature efficiency.
- GSHP has a longer heating cycle but more than offset by reduced recycle time. Slightly reduced COP?
- UFH unaffected. Small amounts of this higher temperature water are mixed in on a more frequent basis than GSHP recycle times to maintain close to 35c.

Is that about right?

Hi Patrol,
Thanks for the explanation. I now get what a buffer tank and a mixer valve does. I can't fit a buffer tank due to physical space, but I have someone coming to fit the right mixer valve for the GSHP. Can I ask one question about the mixer valve though, does the one controllerd by the GSHP switch on and off, or does it vary the proportion? I think from the wiring that it is either Open (water enters the UFH from the GSHP and from the UFH return), or Closed (water only enters from the GSHP).

On another note, I'm rather proud of myself as I've managed to get the actuator which is on one of the 4 UFH loops to work off the stat in that room. It was all wired up by the previous occupant/electrician, but they'd wired it wrong between the wiring centre and the stat.

Apologies for the many replies. Can't work out how to reply in one go :-)

Patrol

I don't know Beardy. The manual indicates there is an open temperature and a close temperature with a neutral zone between the two, I had assumed this meant it was on/off rather than mixing but could be wrong.

beardymarrow

Patrol wrote: »

I don't know Beardy. The manual indicates there is an open temperature and a close temperature with a neutral zone between the two, I had assumed this meant it was on/off rather than mixing but could be wrong.

Thanks mate, that's how it looked to me as well, and makes sense from how the wiring looks. Cheers!

lovesgshp

Did you get your mixer valve fitted Beardy?
Would be interesting to see how the readings went.

beardymarrow

lovesgshp wrote: »

Did you get your mixer valve fitted Beardy?
Would be interesting to see how the readings went.

Hi, no not had it done yet. It's booked in for 20th Jan. Fingers crossed it helps a lot (it can't hurt, that's for sure). I'll be sure to update as soon as it's done.

lovesgshp

3 way valve issues on IVT/Worcester Bosch heatpumps.

There have been a few issues with these valves, as can be seen from earlier posts. I have also had a problem, firstly in Jan 2014 and then again in Dec 2014. In both cases I have managed to resolve the issue, albeit with the help of WD40.
The recommended replacement is the LK Armatur, which Beardy and Patrol have used. According to our engineers, this has a virtual 100% operating record.
Have mine here now, ready to be fitted!!!

Patrol

I came home this evening to find a red flashing light (first one since installation), DHW at 32c and acknowledging the alarm results in another one as soon as the restart timer reaches zero. I sense a call to the supplier to see what out of warranty options there are.

Alarm MB1 Compr. Circ. Switch.
Motor circuit switch for compr has triggered.
Possible cause.
* The set value is too low.
* Compressor error.
* Overload on power line.
* Temporarily (sic) error.