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chrisneedham
31-08-2013, 05:27 PM
hello guys,

We have a GSHP (brine/water) nominally rated at 31kW (heat output) supplying four apartments of about 600m2 floor area in total.

The GSHP was manufactured by ERW (Germany) in 2006.

Main component - a Copeland ZR16M3E-TWD-522 scroll compressor - R407C refrigerant, POE oil.

For several years the GSHP had been used to heat both DHW and UFH. The UFH had not been properly commissioned and the majority of the zones valves were opened less than 20%. So, heating the DHW, combined with a high temperature hot side output to the UFH (about 42 to 45 C) and low flow rates (about 30 l/min - only one circulation pump for all 4 apartments!), meant the compressor tripped out at least once daily when heating DHW, and was short cycling (more than 10 starts per hour, even in coldest winter) when feeding the UFH.

The filter-dryer indicator is showing purple = "wet" (dry/wet/caution), and the oil level in the system is probably too low - there was some green slime at the bottom of the casing 2 years ago - cleaned up, and hasn't re-appeared.

The GSHP seems to be running OK now, the UFH temperatures are (more than) hot enough in winter. DHW heating by GSHP is now limited to 43 C, then by electric immersion heater. So the compressor no longer trips, and it's maximum electrical load is about 9kW, so within spec. Hot side output to the UFH is about 38 C.

I have a couple of questions;

1. Is there any way of telling how much, if any, wear/damage might have been caused by the years of short-cycling, "wet" oil, and possible low oil level ?

2. Can the refrigerant and POE oil be replaced, along with the filter-dryer, in situ, and would it be advisable to do that ?

The German manufacture is asking 1,100 just for travel/hotel costs (they're based about 4 hours drive from us), so we're thinking of getting a local air-conditioning/refrigeration company to do any work.

Thanks in advance for any advice.

Greetings from Brussels

Chris

MikeHolm
31-08-2013, 11:22 PM
A short answer is to get Peter (a mod here) to look at it. Smart fellow and he is in Belguim.

The second thing is that I hope there is a buffer tank between the heat pump and the floors. The floors should be on weather compensation control. With this you will have more control over the starts.

chrisneedham
01-09-2013, 06:28 AM
Thanks Mike, I'll do that.

There is weather compensation, but no buffer tank.

System designer and builder fell out and left us with a half-baked system :-(

Rob White
01-09-2013, 09:27 AM
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There is no easy way of measuring any damage to the compressor
but it is possible to do the repairs you state (changing dryer and oil).

It would be a relatively easy job for any company that has a good
refrigeration engineer. You should find someone local who will charge
a day rate and parts.

The whole system does need commissioning properly though, flow
rates and flow temperatures need balancing so a good heat-pump
company should be able to do all the work, including the refrigeration
work.

Regards

Rob

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