Vaillant EcoTec Pressure loss

[Zooks]

Hi, I'm new to this forum and have a problem with our heating system. The boiler is a Vaillant EcoTec Plus 36kW and was new Jan 24. The CH water pressure drops over a 10 day - 2 week period to less than 0.8 bar then the boiler throws an error.

I can't be 100% sure but it seems like its done this since it was serviced 5 weeks ago. The problem is our installer and servicing engineer is notoriously hard to get hold of and is not responding to calls/messages. Not dissing him as he's flat out busy but it could be weeks before I hear from him.

For my part I have checked my rads and pipework and can see no signs of a leak or dampness.

 

So in the interim and after doing a bit of searching on here is this a good idea?

I intended to re-pressurize the system to normal then switch off the boiler, isolate the flow/return pipes at the boiler and leave it off a couple of days to see if the boiler drops pressure.

Question 1 - my only way of seeing the pressure is to turn it back on. Is it safe to do this with the flow/return shut off (obviously heating off)? If the boiler pressure hasn't dropped then I can assume its my pipework or rads and vice versa.

Question 2 - Can the boiler be used to provide just hot water with the flow/return isolated so I can test it over a longer period as its a slow pressure loss?

 

Or should I just call Vaillant and plead ignorance!

 

Thanks for your help

 

 

[Nickfromwales]

Hi. The pressure gauge will be isolated from the heating circuit if you isolate both the flow and return under the boiler, so you’ll not be able to tell where pressure is being lost unless it’s from the boiler itself.

 

Is this a new boiler on existing rads and pipework?

 

I would just top up again and monitor and wait for your chap to attend, Vaillant won’t be able to advise much better over the phone as they didn’t install it.

 

If it’s a replacement boiler then it’s likely there’s a leak where you can’t see it, so this may need some thorough investigation to establish what’s wrong.

 

There will be a blow off pipe, usually 15mm copper, going to the outside of the wall behind the boiler. You can check to see if the blow off (PRV) is opening and letting water out (passing) as that could have failed early.

 

I wouldn’t interfere with the valves under the boiler as your installer may then try to blame you for misadventure etc.

 

Best to just top up and wait for your chap tbh. 
 

Oh, and absolutely DO NOT use the hot water with the heating isolated. The boiler will perform an overrun cycle to dissipate heat and you’ll be preventing that from happening. 

[Zooks]

Ok thanks Nick. Its was a replacement boiler on an existing CH system.I had no pressure loss at all untill recently but then noticed it was falling so topped it up but it now losing about 0.5bar over 10 day so somethings amiss. Its draining into undersink plumbing so i'll cherck that.