Ground Source Heat Pumps

JHen1

JHen1 said:

Hi My IVT Greenline HT Plus C7M is alarming with a "low pressure switch alarm". I have pressed "Ackn", but it alarmed again shortly after. Looking at the manual there are serveral causes. I can see the expansion vessel is about 60% full (but its about 80% when serviced).

As an update to my earlier post, AltoEnergy have got back to me, and after a short call, diagnosed the issue as a failed P3 Pump. I have arranged this to be replaced by them and have now have the IVT set to use the immersion heater function.

Strummer22

JHen1 said:

JHen1 said:

Hi My IVT Greenline HT Plus C7M is alarming with a "low pressure switch alarm". I have pressed "Ackn", but it alarmed again shortly after. Looking at the manual there are serveral causes. I can see the expansion vessel is about 60% full (but its about 80% when serviced).

As an update to my earlier post, AltoEnergy have got back to me, and after a short call, diagnosed the issue as a failed P3 Pump. I have arranged this to be replaced by them and have now have the IVT set to use the immersion heater function.

What are you doing for space heating in the meantime?

beardymarrow

Strummer22 said:

JHen1 said:

JHen1 said:

Hi My IVT Greenline HT Plus C7M is alarming with a "low pressure switch alarm". I have pressed "Ackn", but it alarmed again shortly after. Looking at the manual there are serveral causes. I can see the expansion vessel is about 60% full (but its about 80% when serviced).

As an update to my earlier post, AltoEnergy have got back to me, and after a short call, diagnosed the issue as a failed P3 Pump. I have arranged this to be replaced by them and have now have the IVT set to use the immersion heater function.

What are you doing for space heating in the meantime?

Nice. That makes sense as low flow over the heat exchanger on the cold side could cause it. 
Could still use it on immersion for space heating. 

Patrol

Strummer22 said:

JHen1 said:

JHen1 said:

Hi My IVT Greenline HT Plus C7M is alarming with a "low pressure switch alarm". I have pressed "Ackn", but it alarmed again shortly after. Looking at the manual there are serveral causes. I can see the expansion vessel is about 60% full (but its about 80% when serviced).

As an update to my earlier post, AltoEnergy have got back to me, and after a short call, diagnosed the issue as a failed P3 Pump. I have arranged this to be replaced by them and have now have the IVT set to use the immersion heater function.

What are you doing for space heating in the meantime?

By immersion heater I believe JHen1 is describing the additional heat function provided by the inbuilt cassette. It will provide both hot water and heating capability albeit at a COP of 1 rather than the higher efficiency achieved via ground loop

(I could be mistaken but a check of the manual indicates to me that pump is required for ground loop circulation)

If you want to see the impact - this image is my electricity tracking since installation. I disabled my ground loop between 15 Jan-14 Feb 2015 when my soft start failed. It's the red spike heading towards daily 75kWh so hopefully the pump will be sorted quickly and the ground loop can be re-enabled 

Strummer22

I see. I don't think my GSHP has backup for space heating, only for DHW. For heating the output has hit 15+ kW at times (unit rated to 22 kW), I don't think it can draw enough power to heat the house with a COP of 1! In the recent cold weather my daily heat generation was well over 120 kWh so not too expensive with a COP of 4+ but mighty scary £30 per day at a COP of 1. 

We have a wood burner to keep at least the main living space warm if the central heating isn't functioning. 

beardymarrow

Patrol said:

Strummer22 said:

JHen1 said:

JHen1 said:

Hi My IVT Greenline HT Plus C7M is alarming with a "low pressure switch alarm". I have pressed "Ackn", but it alarmed again shortly after. Looking at the manual there are serveral causes. I can see the expansion vessel is about 60% full (but its about 80% when serviced).

As an update to my earlier post, AltoEnergy have got back to me, and after a short call, diagnosed the issue as a failed P3 Pump. I have arranged this to be replaced by them and have now have the IVT set to use the immersion heater function.

What are you doing for space heating in the meantime?

By immersion heater I believe JHen1 is describing the additional heat function provided by the inbuilt cassette. It will provide both hot water and heating capability albeit at a COP of 1 rather than the higher efficiency achieved via ground loop

(I could be mistaken but a check of the manual indicates to me that pump is required for ground loop circulation)

If you want to see the impact - this image is my electricity tracking since installation. I disabled my ground loop between 15 Jan-14 Feb 2015 when my soft start failed. It's the red spike heading towards daily 75kWh so hopefully the pump will be sorted quickly and the ground loop can be re-enabled 

Yep, P3 is the cold loop. 

JHen1

"By immersion heater I believe JHen1 is describing the additional heat function provided by the inbuilt cassette."

Yes, this is correct. I was aware that this would obviously be more expensive to run but at least I still have heating and hot water. Funny thing is, by the time I identified the fault at 9am to when AltoEnergy called to diagnose and turn on the "immersion" function, around 2pm, I could still feel some heat occasionally in the rads and the house did not get cold. I also have wood burner, but that only really heats the front room. Also our tiled floor with underfloor heating (from the GSHP) also did not get cold.

I usually keep a track of my electric usage and it appears my total daily usage has doubled. Let's hope they can arrange an engineer soon.

JHen1

With regards to the replacing of the P3, is this something I can replace myself? I am waiting for a date for the engineer, and Ideally I'd want the engineer to replace, but if there is a long delay then ...

beardymarrow

JHen1 said:

With regards to the replacing of the P3, is this something I can replace myself? I am waiting for a date for the engineer, and Ideally I'd want the engineer to replace, but if there is a long delay then ...

I would do it myself if it was a long delay, but depends on how confident you are with plumbing. If not, any plumber would be able to do it. They are just the same as a central heating pump to do.
You just need to buy a replacement model that's identical. Shut the valves, unscrew (slowly as some water will leak, and depending on how identical the new one is you might not need to remove the fitting from the pipes, just pull the motor off), replace, refill and open valves. Try not to let any of the water leak into the ground as it's got glycol in it.

It's a Wilo TOP-S25/7.5 on my E9 (it'll be in the back right of yours behind the control box). I think it's this one on yours - https://www.ivtspares.co.uk/collections/ivt-greenline-ht-c7-rf-1x230v/products/ivtsp10180, which looks like a more modern version of what I have.

JHen1

Hope you don't mind the update. AltoEnergy were able to get a engineer out today. He did some tests and he could get the pump running, which led him to think the TXV valve was faulty. This is located just under the P3 pump. He said this can sometimes get (wrong terminology) cross contaminated with oil from the condenser (not his words, and Ive probably got that all wrong ) After some extra testing he determined is was in fact the P3 pump as this was failing when he did some specific test on it. He did state the TXV issue can be misinterpreted when the unit has been off for some time - like started a vintage car that has not been started for a while, and as this had been off since Friday... Anyhow pleased with the service from the engineer and AltoEnergy. Also, glad I did not eventually try to replace the pump, as it was rusted on and he need a blow torch to "convince" it off

I think I've sad this previously, but I'm very grateful for this forum and for the fantastic advise/responses from the members.