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View Full Version : Massive water leak into refridgerant on GSHP







JackPreacher
21-04-2013, 04:14 PM
Hello all,
I'm making my first post here and hope that the problems that my IVT C7 GSHP (single phase, 240vac, 7kW output) have may be interesting.....not only in the repair of the unit but also the cause.

SCENARIO
1. I installed the IVT Greenline C7E a few weeks back - it is designed for a ground loop of glycol but I plumbed it directly with fell water at 125psi. It is effectively an open loop water source heat pump now....without the auxiliary heat exchanger.
2. Incoming fell water was at 9C, outgoing was 4C. All worked extremely well.
3. Last week the low pressure switch tripped repeatedly and the sight glass went murky yellow in the refridgerant line.
4. With the power off, I noticed bubbling in the sight glass whenever I opened the valve to let the fell water (glycol side) through the plate heat exchanger (PHX). I assume the PHX is leaking between the refridgerant and the fell water.
5. The scroll compressor started to make terrible noises - I shut it off before too much damage could occur, but I assume it is liquid slugging.
6. There is no warranty on this HP as I bought it secondhand, so I have to fix it. I have a 2 stage vacuum pump and refridgerant recovery rig......no gauges yet though. It's R401C, 1.4kg

Two questions:
(i) When recovering R401C does ithave to be discarded?
(ii) Will the compressor oil be contaminated with so much moisture ingress into the LP side?


Thanks in advance

JackPreacher
21-04-2013, 04:16 PM
Sorry, it's R407C, not 401!

chemi-cool
21-04-2013, 05:04 PM
In your case there is nothing to recover, or to repair.
The cause as I see it, is not following instuctions and not using ground loop at much lower pressure.

r.bartlett
21-04-2013, 05:20 PM
so you hold the necessary qualifications?

frank
21-04-2013, 06:25 PM
I would connect a gauge line (old one) to the refrigerant side and see if H2O comes out.....next step depends on the result..

why does you ground loop operate at 8bar?

JackPreacher
21-04-2013, 07:12 PM
The cause as I see it, is not following instuctions and not using ground loop at much lower pressure.Agreed, it is operator error.
I had originally de-pressurised the fell supply with an interim cistern that filled from a high flow float valve then used the IVT's ground loop pump to circulate the fell water through the PHX and out to exhaust to the stream. ...and then a brainwave - why not use the water directly and exhaust it to a small cross flow turbine that I've built..? :eek:


In your case there is nothing to recover, or to repair.

That could be great news or terrible news! Would you expand a little on that chemi-cool?

...much appreciate your taking the time to respond

JackPreacher
21-04-2013, 07:21 PM
so you hold the necessary qualifications?

No, my qualifications are in Chemical/Materials engineering. This has happened in the last few days and, living in the wilderness, it'll be a while before I can get someone out who has 'F Gas' accreditation.. I want to get all the moisture out asap before acids form i the motor windings.

JackPreacher
21-04-2013, 07:33 PM
I would connect a gauge line (old one) to the refrigerant side and see if H2O comes out.....next step depends on the result..
Thanks Frank, I'll get onto that in the morning:)

why does you ground loop operate at 8bar?
See answer above.
I took a gamble that the PHX would have a pressure rating of at least 20Bar so figured 8Bar wasn't too bad.
Wrong:mad:
I'm trying to track down a datasheet for the PHX as we speech......

The previous owner had complained that the low pressure switch was always coming on - and that was the original suppliers installation. That was why he sold it. The reason that the previous installation was doomed [according to the installers] was because the ground loop was leaking. The previous owner had taken responsibility for digging out and preparing the trenches for the vertical radiator style of collectors - hence the leaks - he had used compression fittings underground

chemi-cool
21-04-2013, 07:40 PM
I took a gamble that the PHX would have a pressure rating of at least 20Bar

Wrong, you read the manufacturer little note on the PHX,

monkey spanners
21-04-2013, 07:49 PM
Could have been corrosion that led to the failure, though the pressure wouldn't have helped. Had some plate heat exchangers fail in dairys when the customer switched to bore hole water.

Systems most likely scrap now. You are lucky the compressor didn't explode if its full of water (can become full of steam as it shorts out the electrical supply).

The Viking
21-04-2013, 08:32 PM
Lesson to be learnt:
If the spec calls for a glycol mixture...

In your case, when the water was leaving at +4C the refrigerant and the plate between the two was most likely at -6C or below. That's why you need the antifreeze as otherwise ice will form on the plate and continue to grow until something breaks.

Pressure rating of the PHE has nothing to do with the failure, ICE will move whatever comes in it's path..

The nothing to reclaim or repair comment above, that was tongue in cheek, most likely your refrigerant has left the system via the water circuit and any repair will cost more than a new unit would. Sorry.

:cool:

JackPreacher
21-04-2013, 08:34 PM
Could have been corrosion that led to the failure, though the pressure wouldn't have helped
..or ice buildup?

Systems most likely scrap now. You are lucky the compressor didn't explode if its full of water (can become full of steam as it shorts out the electrical supply).
Do you mean the whole system or just the PHX?

The Viking
21-04-2013, 09:47 PM
Do you mean the whole system or just the PHX?

Sadly, if your domestic size GSHP has been flooded then the cost of the repair will be greater than the cost of a new unit. So, yes what MS refers to above is the whole system. Sorry.
Even for someone like myself with all the tools needed in the van, nett costs on spares and "free" experienced labour it is not a given that we would opt to repair a system like this after it been flooded.

Another thing to bear in mind is that any moisture in your system will turn the oil acidic, so the oil is now eating away on both the electrical insulation in the compressor and all the metal the oil is in contact with.

:cool:

JackPreacher
21-04-2013, 09:52 PM
Lesson to be learnt:
If the spec calls for a glycol mixture...

In your case, when the water was leaving at +4C the refrigerant and the plate between the two was most likely at -6C or below. That's why you need the antifreeze as otherwise ice will form on the plate and continue to grow until something breaks.

Pressure rating of the PHE has nothing to do with the failure, ICE will move whatever comes in it's path..

The nothing to reclaim or repair comment above, that was tongue in cheek, most likely your refrigerant has left the system via the water circuit and any repair will cost more than a new unit would. Sorry.

:cool:

Lesson harshly learnt.
Well, nowt to lose to see if I can repair it. I'll document the procedures anyway, even if to warn others not to try messing with design parameters.

TBC

joe-ice
21-04-2013, 10:25 PM
Your only option is to remove heat exchanger , remove compressor and and remove oil from it ,prob more water than oil at this stage ,blow out all pipework and compressor with nitrogen a few times,refit compressor with new oil (polyester)added,blank off heat exchanger pipes and vacuum system for long time down to 300 microns if have gauge. Break vacuum with nitrogen flushing ,change drier,fit new hx and vacuum again for long time and recharge. You will have to put in some protection to stop water going below 5 degrees to stop it freezing again

JackPreacher
22-04-2013, 08:48 AM
Thanks Joe, you've just confirmed what I didn't want to have to do - that is. removing the compressor.

Till later.

hyperion
22-04-2013, 01:58 PM
You may have a slight problem legally obtaining R401C as not all wholesalers stock this grade. Whilst you may be technically competent, please be very carefull when handling and using OFN for pressure testing etc.
You will need to seek assistance from a qualified refrigerant handling engineer before attempting to introduce the new refrigerant, if you can get any.
At the end of the day, you may still have a non-working system once moisture/water has got in.

JackPreacher
22-04-2013, 03:04 PM
You may have a slight problem legally obtaining R401C as not all wholesalers stock this grade. Whilst you may be technically competent, please be very carefull when handling and using OFN for pressure testing etc.
You will need to seek assistance from a qualified refrigerant handling engineer before attempting to introduce the new refrigerant, if you can get any.
At the end of the day, you may still have a non-working system once moisture/water has got in.

Point taken Hyperion, thanks.:)
I've got a tech in mind to do the actual pressure testing and re-charge of R407C. As there is no refrigerant left I'm comfortable with the strip-down and checking the compressor oil and damage to the system in general. As the pump was secondhand it was no surprise to find a cracked top and casing on the start capacitor. I've taken a few photos - I'll post them this evening.

RusBuka
22-04-2013, 04:02 PM
https://www.youtube.com/watch?v=IIPMQbs9EZg
https://www.youtube.com/watch?v=RmmWDcl_JQ4

)

hyperion
23-04-2013, 10:17 AM
Now that you mention that the system uses R407C, this will be much easier to obtain. Still think that this could be a labour of love with potentially the wrong outcome.

hyperion
23-04-2013, 10:20 AM
Russ,
Like the videos, just a slight problem with moisture!

JackPreacher
23-04-2013, 12:48 PM
Well Chaps and Lasses, here goes.....

10259
The whole system had to be drained down. When I installed the system I had added an easy access drain down pipe run as the IVT isn't easy to drain down without removing all the casements.


10263
Next up was to double check there was no system pressure. As expected, the refrigerant has dissolved into the fell water and de-pressurised across the the leaking heat exchanger. The gauge showed no pressure.


10260
The electrical looms, connections, sensors etc all have to be disconnected from the heat pump before it can be removed from the chassis. The Heat Pump sits on a sprung tray that is bolted to the chassis. In order to pull the unit out backwards from the chassis the ground loop and central heating pipes must be drained and removed.

10261
The compressor electrics are straightforward to disconnect. I labelled everything as I went, and these photos will help with the re-assembly.

10262

JackPreacher
23-04-2013, 12:52 PM
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JackPreacher
23-04-2013, 12:54 PM
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The Viking
23-04-2013, 12:56 PM
Hi Jack,
Thanks for keeping us updated.

If you manage to get it up and running again, what modifications do you have in mind for the fell water loop?

.

JackPreacher
23-04-2013, 12:57 PM
10274

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JackPreacher
23-04-2013, 01:00 PM
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JackPreacher
23-04-2013, 01:02 PM
10284

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JackPreacher
23-04-2013, 01:08 PM
10289

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That's it for now. The compressor is sitting in fresh oil. I can't be sure the old stuff is all out but around 5 litres [guesstimate] of watery/oily/milky fluid drained out of it....yuk!
Still, I can fire it up and test it to see if it is reusable.
The rest of the refrigerant circuit is still to be drained but it can't do any more harm than has already happened. I'll drain that out on Friday. I have limited time to devote to this project as it is at a property that we only stay at occasionally.

TBC

JackPreacher
23-04-2013, 01:23 PM
Hi Jack,
Thanks for keeping us updated.

If you manage to get it up and running again, what modifications do you have in mind for the fell water loop?

.

...hmmmmm.....
I'm open to suggestions!!

Firstly, the fell water is a fabulous resource, and we're very lucky to have it, but I think the HP will have to make do with exhaust water from the hydro-turbine.

The flow rate is @minimum=5 litres/sec @maximum=13 litres/sec and the temperature is no less than 6.5C

As you mentioned, ice was probably the killer here, and I never considered it could form at the outlet temperatures I was getting.
So, an auxiliary heat exchanger will isolate the glycol mix, but what kind of HX? Not a Plate Heat Ex!! Maybe a large copper array submerged in the outflow tank from the turbine....
What do you think?

JackPreacher
24-04-2013, 07:20 PM
I've had a think about what to do about the glycol loop when I fix the HP.

First option, and not the prettiest, is to build a copper array with 10mm copper tube with fins (not finned copper tube though) that extends from the line set out the back of the HP and is mounted in an oil drum. The refrigerant will be pumped directly through the array whilst the fell water fills the barrel from the top and exits at the bottom. I would estimate between 6 to 8 gallons (imp) a minute could be attained with gravity assist.
The advantage of this setup would be the omission of a separate glycol loop.

Second option is to run a glycol loop through a replacement PHX down to the turbine room which is 26m away. There are 2 off 25mm mdpe lines buried between the turbine room and the boiler room already. In the turbine room a large copper array will be immersed in the fell water exhausted from the turbine.

I would really appreciate some members' opinions on either of these 'solutions'

Thanks

chemi-cool
24-04-2013, 08:10 PM
some drawings will help

The Viking
25-04-2013, 10:02 AM
Jack,

First and most important; 10mm (water) Cu tube is not suitable for refrigerant.

But also, if you do intend to keep this as a semi DIY project you will be better of replacing the PHE "like for like" and then play with a new glycol loop.

And, for the same reason your PHE failed, your "drum evaporator" is likely to become a block of ice unless you modify the controls of the heatpump to incoporate some sort of defrost cycle.

:cool:

JackPreacher
25-04-2013, 11:44 AM
Thanks Viking. I'll look at the Maths over the weekend and figure out the size of array for the glycol loop exchanger......and post up here with drawings and photos.

One issue I'm having is difficulty in acquiring the data sheet for the PHX that needs replacing, let alone actually speaking to a sales tech who can supply said item. ..and if the compressor needs replacing the original supplier/installer company is very difficult to speak to about parts, even though it's one of their heatpumps, albeit sold on to me of course!

stufus
25-04-2013, 06:09 PM
At a glance that looks like a mitsubish electric compressor , shouldn't be to dificult to source if required.
And the bphe looks to be an alfa laval again shouldn't be hard to get your mitts on.

Cheers
Stu

JackPreacher
01-05-2013, 01:42 AM
Thanks Stufus - indeed you were bang on about the PHX - the busted one was covered in Armaflex but the original installer had written the serial number on a stickie......a quick call to Alfa Laval and the serial checked out..........
..naturally, after patting myself on the back for joining R-E and getting essential info from generous minded engineers...particularly from you, Stufus (Re: Alfa Laval), I promptly found the full manufacturer details on the Other PHX.........:eek:


It is a Mitsubishi compressor. I haven't fired it up yet .........am hoping I caught it before it pulverised itself.

TBC

r.bartlett
01-05-2013, 06:08 AM
put the compressor in the oven over night around bake around 70c -that will get rid of the remaining moisture before you try firing it up..

JackPreacher
02-05-2013, 09:43 AM
put the compressor in the oven over night around bake around 70c -that will get rid of the remaining moisture before you try firing it up..

Seriously?:eek:

JackPreacher
04-05-2013, 06:09 PM
The price came in for the PHX...


532.80 including FAT and delivery. 4 weeks to wait. Can't do a lot until then:mad:

pilko
08-05-2013, 10:37 AM
Hi Jack,

This is pilko from Well water assisted ASHP thread . What does your final HX look like? Would it work for me as in my last post? -- if so, do you have any details?
--- After looking at my last post I would appreciate any comments and recommendations.

---Regards,

---pilko.

JackPreacher
08-05-2013, 12:45 PM
Morning Pilko......this is a disaster zone - have you got a hard hat on??? !

The HX to transfer heat from the fell water to the Glycol loop hasn't been fabricated yet as the Heat Pump is still in bits in my workshop - I'll fire up the compressor ASAP to see if it survived (I'm optimistic it has) and, if it passes the electrical examination I'll order the replacement PHX and then build the HX we're discussing on our two threads.

I've built copper HX arrays for DHW applications in the past but because of the high temperature differentials involved it was always predictable that they would perform, however, the low differential temps between the fell water (or your spring water) and the Glycol means a bit more thought needs to be applied to the design. In my case the copper HX has to substitute 800m of 40mm GSHP pipe and I only have a 4ftx3ftx2ft volume to fit it into. I will use an array of parallel coils of 10mm copper and keep an eye on the flow rate and pressure drop so that the Glycol runs through the HX at the optimum rate (no figures figured yet!) and also ensure the Glycol runs into the exit side of the Turbine exhaust and exits at the intake side, if that makes sense.....just like the counter flow a plate heat exchanger utilises.

Last summer, when we bought the HP I built a copper array and sunk it into a small pond we have - using a Glycol loop. The array was a 15m length of copper tube that ran in zig zag! It worked for around 10minutes at a time before the LP switched in due to the Glycol getting down to -7C or thereabouts (actual figures are a distant memory). I knew it would work with the correctly sized array so, using a PHX, I ran fell water through the PHX (an additional external one rated at 44kW) which kept the Glycol at around -2C at the outgoing collector sensor and coming back in at 1C, or thereabouts. It was after this that I ran the fell water directly through the HP (....and it says not to in the manual....) that the problems occurred.

To summarise, I feel happy to experiment with the sizing of the copper array HX for the Glycol loop but would never, ever again use a PHX. As long as your HP sensors are working accurately (secured and insulated in the correct location) then extending your glycol loop into an open HX should be safe. I noticed someone suggested you use either Air source Or your spring water. After thinking about this I agree.....far fewer controls required and a better performance in the colder months, plus you could always switch over to Air source if required. If you have a maximum of 5kW available from your spring water surely you'll get a much better COP when air temps are below freezing........and what about getting an old working HP from a breakers yard and having trial with that? ....


......wish I had....

pilko
08-05-2013, 02:50 PM
Hi Jack,
I don't mean to hijack your thread, it's just that there are similarities.
--- In post 41 of my thread I have eliminated the glycol loop and gone with a tubes-in-a-tub HX as per MadFridgie's
suggestions in post 40.
--- What are your thoughts on the system, including the second RV?

JackPreacher
08-05-2013, 03:05 PM
Complicated! I'm going to go back and re-read your thread to double check a few things but my initial thoughts are as follows: (..and I Love experimenting.....)
1. Trial one modification at a time if you have the facilities.
2. Mad, The Viking and all the other more active members who have already commented on your thread really know their onions so their opinion is worth a lot more than mine!!....but thanks for asking.
3. If you install the RV then check the manufacturers preferred orientation in the lineset.

Does this unit heat/cool your property as we speech?