Vaillant ecomax 835

gasmarkone · 27 Apr 2006

Hi, got a bit lost on one of these. Problem with HW, it always comes on and heats up for 1 to 2 mins, then the burner modulates down to low rate. Water cools off but burner remains on low. Thermistors changed, pcb changed [vaillant said!], diverter changed, no joy. Any ideas?
PS the heating seems to do same, but does heat up eventually.

Agile · 27 Apr 2006

Which part of Dorset?

From what you have said I would want to measure the temperatures around the boiler.

I would suspect that there is a pump or flow problem. Have you taken the pump head out to inspect the impeller?

Did it do this from the moment it was fitted?

Tony

gasmarkone · 27 Apr 2006

Snobby Sherborne! Thanks for the reply. The boiler is reported to have worked for 2-3 yrs, just went cold whilst customer in shower. Had the plate H/EX out, looked clean/clear. Pump spins [took screw out]. The primary flow/return both heat up for 1-2 mins, water hot. Then burner modulates, f/r go cold, h/w cold. Interesting that you say pump, cos it makes a buzz/hum which customer has not heard b4. I know that it has variable speed, but customer did not report heating problem, all radiators getting hot.

Agile · 27 Apr 2006

You may have spun it but you have not inspected the impeller.

In any case if its making an unusual noise that that is an added pointer towards my (remote) diagnosis!!!

Tony

Ed Sirett · 28 Apr 2006

This is an unusual fault.

Here are some of the things I can think of that might help to get a handle on it:

Have you tried the full heat test mode? Pushing the + & - simultaneously this will not modulate and will only cut when the primary flow is at its atop limit (87C ?)

You could try replacing the 'cap' in the pump I think these are more or less interchangeable between most domestic pumps.

I'm wondering if perhaps the pump can properly do the part 1/3 or 2/3 power settings and this leads to problems.

HTH

gasmarkone · 15 May 2006

Hi, just for the record, Vaillant came to this one so as not to keep the customer without HW for too long. It was the pump, so Agile & Ed you can allow yourselves a smug smile. Just as well sell your vans & do the job by phone

. Well, I thought I was getting a bit of confidence back after a 10yr absence from this line of work, not feeling so smart now!

Agile · 16 May 2006

Thanks for letting us know it was indeed the pump.

I am by nature curious and I would love to know why you did not go back and look at the pump impeller after I suggested it was at fault. Why did you apparently give up so easily when I had pointed you in that direction?

If the impeller was clean then you would have needed to test the torque with a finger.

Tony

gasmarkone · 16 May 2006

Well, I'm not the boss. Not having bits on the van like a specialist engineer, this job started to run on a bit. Time customer waits for our first call [still pretty busy], then order thermistors, recall, pcb, recall etc, it was thought best to learn from this one. I had the cap off the pump to observe it spinning when in use, but I cant see quite what it was doing wrong. With 2 leads coming from it on to the pcb, it obviously interacts in a more complex way than you're common or garden combi pump! I thought if CH was reported OK, and flow/return cool when burner on low modulation, it couldn't be doing too much wrong [maybe too fast flow?]. So as ever the customer had that 'told you so' look when the pump was changed.

Ah well, another lesson in life!

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Vaillant ecomax 835

Similar threads