Danfoss DHP-AQ 16kW Motor Protection Unit (Overload Relay)

[Worcester]

Anyone know the specification of these units - is it the Schneider LR22 or LR32?

The LR22 is 16A, 24A http://uk.farnell.com/schneider-electric-telemecanique/lrd22/relay-overload-16-24a/dp/3622691

and the LR32 23A, 32A http://uk.farnell.com/schneider-electric-telemecanique/lrd32/relay-overload-23-32a/dp/3622708

We've got one failing on a custards site ( 1 hour each way ..), and I want to order it online over the weekend. (Farnell stock them)

Can't find any details in the manuals whatsoever, and Danfoss support in the UK is non-existent (they've subbed it out to a third party)

Its a 16kW Air Source Heat Pump.

[Kenneth199]

Whats the motor rated for? 230v or 400v? is 16kw the power usage from compressor or is it heat/cold capacity?

Have you figured out why the old one failed? is the 96 and 97 connected to A1 to contactor?

[Worcester]

Thanks for the response
Single phase 230V
16kW is the model number, so it's a theoretical output capacity A7/W35
Not yet ! It's possibly a failing compressor, though due to the time to site we want to take a spare one with us..(They're not expensive, just don't want to buy two really) We'll run tests on site to further identify the cause.
Wiring diagram attached
13988

[Kenneth199]

It says the compressor is rated 5.5kw at 230v single phase. which is 23.9A.
The lrd22 goes from 16-24A and the lrd32 is 23-32A.

I think its lrd22, but i would take one of each if not 100% sure.

[Quality]

The compressor will be causing the correct operation of the overload hence the overload is doing its job. I have replaced loads of compressors on AQ air source and every other thermia product. But like with any compressor change, all contactors,capacitors etc need to be replaced to give reliable service. But with a small domestic unit and domestic environment cost is always an issue

[Worcester]

It says the compressor is rated 5.5kw at 230v single phase. which is 23.9A.
The lrd22 goes from 16-24A and the lrd32 is 23-32A.
I think its lrd22, but i would take one of each if not 100% sure.

That was my calcs as well, I was trying to avoid having both !


The compressor will be causing the correct operation of the overload hence the overload is doing its job. I have replaced loads of compressors on AQ air source and every other thermia product.

Danfoss have no direct provision for support in the UK, it's contracted out to a third party.
My feeling has been that this site (and another one that is also giving us loads of faults) has a failing compressor, though the local support agent, says that failures of compressors are very rare.
So interesting to hear your comments :)



But like with any compressor change, all contactors,capacitors etc need to be replaced to give reliable service. But with a small domestic unit and domestic environment cost is always an issue

Yep that would be our process as well, spend and get it fixed now rather than chasing tail with other failing components later

[Worcester]

Thanks guys, this will be our first compressor change that we do ourselves, so what components would you normally replaces 'as good practice' at the same time?

Which of these:

Capacitor
Contactor
SoftStart
Motor Protection Relay

Compressor
Drying Filter

Anything else?

Many thx.

[Kenneth199]

I would change all of the above and at start up its important to check the high pressure switch and low pressure switch and other safety switches.
I would also test the oil for acid.
It's also very important to see how the system is operating after compressor change.
There's usual a reason why the compressor fail. Usual its the exv.

[Worcester]

Thanks much appreciated.

Seems like most of the Danfoss so called support team don't have much Air conditioning / Refrigeration side experience, they're OK on the plumbing and controls, lacking understanding of the detailed aspects of the heat generation process / cycle and troubleshooting failing systems.

Hence my posts here, we're aiming to provide a good support service for our customers though we know we need more training, none of the UK suppliers of heat pumps provide any training courses covering fault finding and repairs..

[Grizzly]

Hi Worcester.
Good to read you have benefited from your posts.
I question your last statement.

none of the UK suppliers of heat pumps provide any training courses covering fault finding and repairs
Not sure what / who you include in that?

But I do know Daikin do an advanced fault finding course, and there technical support is quite good!
I agree Danfoss can be a bit sketchy, but that depends upon who's number you have?
And I think the other main manufacturers have similar?

Besides we have our own resident Danfoss Guru nowadays, so feel free to post whenever you like in the future.
There are quite a few who know what they are talking about on here, when it comes to Heat Pumps.

Training is always an issue, hence why so many myself included use the Forum.
Good Luck Grizzly.

[Quality]

You would learn more on a refrigeration course it would give an understanding of a heat pumps from the total opposite view how a plumber see`s them.
Re the AQ compressor failure I am not saying that they fail all the time but they do fail. I replaced one last Friday

[Worcester]

Yep, we'd come to the conclusion it'd have to be a refrigeration course :)

So spent two hours on site today going through the 'official procedure'

Alarms and logs attached for those of you that are interested.

We had a motor protection relay and capacitor with us, half way through we swapped the capacitor anyway. Softstarter was changed on 14/12/2015

Seems to point to possibly shorted windings as the Output start winding from the Softstarter stayed high even after 30 mins.

Anyone else got any pointers? Or further tests to eliminate other causes / confirm it's the compressor?

Thx

13990

[Glenn Moore]

Hi Worcester
Go on Google and type in Why Compressors Fail re Glenn Moore . There are 9 articles in the series . These may help you find the problem otherwise call me Br Glenn

[Worcester]

Hi Glenn,

Awesome; thanks, a great series of articles. Having built racing engines for motorsport ( I'm a hard core engineer :) ), the reasons that you elucidate for that failures make complete sense :) More importantly you list the possible causes, which is always my question, what's the failure, what caused that, how do we ensure it doesn't happen again.

I'll update when we have resolved the issue.

[Quality]

Its mainly during hot water cycle/use as, discharge temperatures regularly rises above the limit which can be raised to 130 degree (super heated vapour temp) when a compressor has to endure this punishment IT will fail