Inconsistent hot water from Vaillant 850

[B91]

In cold snaps, like the current one, our hot water starts off hot but then goes cold. Leave it running best part of a minute and it starts to run hot again.

This only happens during really cold snaps, with daytime temperatures 5C or less.

The boiler is having its annual service tomorrow morning, 16/1, any ideas I can put to the Hometeam service guy?

 

[Bunnyman]

Yes tell him to leave it alone an get a Vaillant specialist in,an what's an 850 ?

 

[Agile]

I think you may be locked into having the Homeserve fellow!

They dont have a very good reputation in the industry for technical excellence!

Explain the symptom and watch his reaction when he has no idea what the problem might be.

I have never heard of a Vaillant 850 !

Tony

 

[B91]

Senior moment there - it's an EcoTEC 835, sorry.

I'm now wondering if this problem is simply cold, dense water draining down to the kitchen while all the hot water is going upstairs to replace it, as that's how it's arranged in this 60 year old house - hot feed goes from bolier room up to bathrooms with a branch back down to the kitchen where this happens. That would seem to fit the cold weather thing.

EDIT - I do mean Hometeam - it's Npower's maintenance plan.

 

[Agile]

Yes, it does just sound as if you have a long route to your boiler from the kitchen. Does it go through the loft? If so could you lag it better?

Best of luck with Npower boiler maintenance.

If you have 20-30 minutes then look through this:-

http://simonthomas.org.uk/npower/

 

[B91]

Yes, it does just sound as if you have a long route to your boiler from the kitchen. Does it go through the loft? If so could you lag it better?

Best of luck with Npower boiler maintenance.

If you have 20-30 minutes then look through this:-

http://simonthomas.org.uk/npower/[/QUOTE]

Well that theory just went up in smoke! Intensely cold last night, and when I went to wash up the breakfast things it started off hot, then went barely warm and stayed that way. Turned tap off, waited a couple of minutes, started again and it was OK. So seems to be a boiler poblem. I'm not optimistic

Yeah, I'm aware of the poor reputation of Hometeam and the like but, TBH, my experience of independents hasn't been exactly confidence inspiring either. I use Hometeam for two reasons - the system has three zones, each with its own motorised valve, and valve failures have been a regular problem. Even they can cope with replacing one of those! And the second reason is if the boiler fails it's their problem, not mine. For £204 a year including a service it's OK for me.

 

[Agile]

In my experience most reasonable boilers create a fault about once every 3-5 years and cost about £200 including a service to repair.

Honeywell style motor valves fail every 7-10 years and I usually repair them for £118 including a service.

I appreciate that having an arrangement like that does give peace of mind to many people. Although many do not seem impressed by their doagnostic skills.

Its unfortunate that anyone can easily become gas registered and offer boiler repair services when they have little or no skills. Many of them just hope they can persuade the owner that the boler is beyond repair and fit a new one for them.

Tony

 

[B91]

Thanks for taking an interest Tony - wish you were local! But maybe I got lucky this morning as Hometeam guy has replaced the heat exchanger seal with the latest design - it was leaking onto the gas valve and should have been replaced last year - and he has also identified a faulty electrode and cable and has gone off for a replacement. I'll make him another cuppa when he gets back

 

[Agile]

He probably worked for BG previously and like many who have left was not very impressed.

He has lots of practical experience of Vaillant boilers and is often able to help people with these.

I hope to go to the Castle Balti again on Saturday.

Tony

 

[B91]

Hey, this is MY thread. Go and yah boo somewhere else!

 

[mickyg]

so what happened about the hot water problem is that solved?
we still dont know what model it is anyway, theres no ecotec 835, its either an ecomax 835 or an ecotec 837/831/824

 

[dangas123]

In cold snaps, like the current one, our hot water starts off hot but then goes cold. Leave it running best part of a minute and it starts to run hot again.

This only happens during really cold snaps, with daytime temperatures 5C or less.

The boiler is having its annual service tomorrow morning, 16/1, any ideas I can put to the Hometeam service guy?

This might be standard operation. Most combis have a pre-heat setting which delivers a quick blast of hot water, the water will then go cold as the water is reheated. you can take it off this setting....read your manufacterers instructions for details

 

[Whitespirit66]

I've had about enough of this wierdo abusing posters

That's DIYnot for you!

 

[B91]

OK, atm it seems that the faults found during the service may have been behind the problem as it hasn't reoccurred since. But of course the temperature has gone up too, so it's hard to be certain. But the previous post about pre-heating also rings bells. It is set to pre-heat, but if that's the explanation it does seem to take a heck of a long run before it comes hot again. OK, it's a large house, but not THAT large I don't think.

So I think - hope - it's been fixed.

V. sorry about the duff info. I was relying on my memory and that has confirmed what my wife says about it It's an EcoMAX 835 and it's been stunningly efficient. My annual Kwh with the old Potterton were 70,000+, now 48,000. Incredible

 

[Whitespirit66]

It's an EcoMAX 835 and it's been stunningly efficient. My annual Kwh with the old Potterton were 70,000+, now 48,000. Incredible

Don't just look at the old potty as a gas guzzler. Many older heat-onlys go on for 30 years, with very few repairs and sometimes little sevicing. You have to cost in the short life, parts and labour needed of modern boilers as well.