View Full Version : IDM Heat Pump high pressure fault

07-03-2013, 10:37 AM
I have a 22kw HGL IDM heat pump running without any problem for 4 years. Recently it came up with a huge pressure fault. I had the installer service the unit and they found one filter clogged on the tank heating circuit. It has not resolved the problem.
Any ideas what the problem could be?
Has anyone got schematics of an IDM heat pump so I can see exactly where this pressure transducer is and what circuit it relates to.

07-03-2013, 06:29 PM
is the pressure fault on the water or fridge side? How do you know it was "huge", did it burst:)

some stuff here:

and a google search for the forum:

https://www.google.ie/search?q=idm+heatpumps&aq=f&oq=idm+heatpumps&sourceid=chrome&ie=UTF-8#hl=en&sclient=psy-ab&q=idm+heatpumps+schematic&oq=idm+heatpumps+schematic&gs_l=serp.3...34008.36250.1.36481. MmtPh0o&psj=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.43287494,d.ZGU&fp=ef4751c410b9f47d&biw=930&bih=453

Have you heat at the minute, are pumps running, water in system etc?


21-03-2013, 06:27 AM
The system is running presently, but intermittently every few weeks I get a low pressure fault. This is then usually followed b high pressure faults as the heat pump cuts in. As I can see the pressure faults are on the compressor circuit.

After the low pressure fault the heat exchanger is frozen. I believe the ground loop is freezing and then causing the heat exchanger to freeze as it is not removing the cold temp fluid.

21-03-2013, 05:58 PM
Being honest it sounds like you have issues with both cooling and heating circuits, you really need it checked, there's only so much we can do remotely, unless you can give us more info;

Ground loop pressures in/out
heating loop pressures in/out
refrigerant suction and discharge pressures/temperatures


Jon Glanfield
23-03-2013, 08:46 AM
It sounds like on the low pressure issue, you may have ground loops that are running too cold, is the array sized correctly or has it extracted too much heat over the lifespan of the system? Is it bore's, slinky's, straights, how much pipe has been installed?

Have you had your glycol level in the loops checked, this can bring up low pressure faults, as can pumps failing or running slow, blocked filters on the ground array side or crystallising of the ground array fluid due to inadequate freeze protection.

On the HP side what hydraulic layout do you have, usually IDM systems have a Hygenik tank with a perforated plate and buffer at the base for the heating, which feeds to compensating pump kits that blend to the correct flow temps.

Have you got an HGL circuit, which is a separate heat exchanger and valve that allows superheated water off the top of the compressor to feed to the top of the Hygenik as a by product whilst the heating is on. The valve may be failing to open correctly and not dissipating sufficient heat to the top of the hygenik, which then finds its way its way into the heating circuit and trips the HP stat.

The valves are pretty robust, and we have encountered PCB failures that lead to inaccurate recruitment of them as opposed to mechanical failure.

If you can provide more detail of layout we may be able to assist.