help needed

[desperate em]

I had a new house built 4 years ago with a solar panel system for heating domestic hot water and an air source heat pump to supply underfloor heating with 2 zones and individual room thermostats. I have had continual problems with the heat pump. when the system works it is fantastic. The company that supplied the system say there is nothing wrong with their system. However the heat pump fails every winter, the company that are responsible for it have replaced it 3 times but every November it goes wrong. I have just waited 11 weeks for the latest machine to be repaired which happened last monday and it hasnt worked since repair (they have not come back to look saying they are waiting to check something on the buffer tank) I suspect this time it needs gassing up with refrigerant as this has happened before. i have back up immersions on both water tanks but only use these when the heat pump fails. I need an independant knowledgeable engineer to carry out an inspection to get to the cause of the problem,or some thoughts from engineers who have encountered similar issues as this is intolerable.

[frank]

What area of the UK are you in EM?

[desperate em]

cambridgeshire, near huntingdon

[mad fridgie]

What make and model of heat pump?

[desperate em]

I am not going to name the make of heat pump as the company have replaced it with a new one under warranty each time it has failed, although it is never the same firm of contractors, they seem to change their areas each year. It is much more that I have reached a stage where i need someone with no vested interest to come and check that the system is installed correctly so I can then try to figure out what to do. The company that supplied the components say that it isnt their system, and as when it works it all works well I can see their point but something must be wrong for the heat pump to break every year usually a week or 2 after the first frosts.

[mad fridgie]

Is it grey heat pump model number RS - *****

There is a reason for asking this

[desperate em]

no its cream

[MikeHolm]

Is it japanese or British or ???

The RE 20 questions game.....

[stufus]

Hi Em
Your not really giving us much to go on here!
You do say the unit is cream, which suggests a couple of probables mainly air con manufacturers.
The nature of the failures would also help and the type of heat pump, monobloc etc.
Failing in low ambient is a bit vague and depending on the system type could be caused by a number either installation or design flaws.
We are all willing to help and the members here have extensive knowledge when it comes to these systems,some in certain brands.
In order for us to help you, you need to help us out with a tad more information.
No one here is going to pass on any of the information from this site to the manufacturers.
Cheers
Stu

[ginger prince]

pm me, i have a red hot heat pump installer in Cambridgeshire who im sure will help you. It was common practice a few years ago to mis apply heat pumps, everyone was doing it it was a steep learning curve.

[desperate em]

you are right, ok here goes but remember I am only a homeowner.
The heat pump is a Unichiller. It was connected to the house in July 2008. In november 2008 I was unhappy that my super new house was not as warm as it should be and after much email traffic and from the installers they suggested the pump had failed. It was running continuosly and doing nothing. It was replaced in the spring of 2009 which I believe was more powerful than the previous but same manufactorer. It failed again in the autumn of 2009. It was repaired but 3 days later failed again, The engineer said it had worked too hard and shattered itself. As he said in his email
The Unichiller had yet once again snapped off the capillary on the discharge line of the reversing valve. This is a version 3 unit which already has a clamp around that area and I cannot understand where that excessive vibration is coming from.

To get the system going I repaired the broken capillary, filter drier, pressure tested the system and regased it with R407C.

In december 2010 we had another problem, this time if I remember correctly it was a refrigerant leak and was easily repaired. It worked fine until November 2011 when it failed. This time I have had the PCB board, the pump and some dry joints replaced (i think). It was repaired a week ago but is not working, it is not generating heat and seems to come on for only 2 hours each evening.
I must stress that unichiller have provided engineers replacements etc under warranty and have done presumably their best but NO ONE seems to know why it keeps failing. I must also reiterate that it is a very good & efficient system when it works, it just seems to be unable to work for more than 9 months at a time.