Worcester Greenstar 25Si DHW problem

[wkdmarty]

Hi, I have a Worcester Greenstar 25Si that has had a problem for the past 3+ years.

I've had engineers out and parts have been replaced, but none have fixed the problem. I'm about to throw it away and never buy a Worcester again.

I was wondering, being as the collective Internet is infinitely more helpful than Worcester Bosch / SSE homeserve, I thought I'd ask here first before spending a fortune on a new boiler.

I had my whole house re-piped and wired from cold water stop valve and pre-consumer unit inclusive. All pipes and rads were brand new, in 2006 and installed was a 25Si Combi.

Since about 2011 or so, there's been a problem with the hot water coming out of the taps. It'll start fine, and carry on fine for about 5 minutes, then, it'll go cold (like the cold water tap), after a minute, it'll go back to hot again.

I have noticed that this only seems to happen when the central heating is on (or has been on?) and I believe only in Eco mode.

To quantify this, we've had no problems taking a shower or filling the bath over the summer, but as soon as the cooler mornings come in and the heating comes on, showers now have the cold minute again.

My wife noticed that this wasn't as prevalent with Eco off (although I'm yet to be convinced).

There is another problem, and I'm wondering if they're connected. Over time pressure sensor goes to 0 bar when the central heating is on, but does not do this over the summer (i.e. it keeps the slightly over 1 bar pressure for 5+ months)

It seems that the system is venting my central heating water for some reason. (I have checked and the cold shower part happens even when the pressure is above the 1bar because now I "fill up" the boiler every morning before I have a shower)

Are these two connected in any way?

As I mentioned above, SSE HomeServe and Worcester have been less than helpful. SSE HS replaced a few parts, then because he couldn't replicate the cold water part said "your central heating has a leak" and left. Bosch just said "out of warranty £300 please".

Can anyone please help me?

Thank you. Marty

 

[twgas]

The pressure issue will be due to an issue with the vessel, needs recharging.
The hot/cold scenario has been done to death, will most likely be the plate heat exchanger being blocked with dirt.

 

[wkdmarty]

So I tested the flow, I'm getting a shade under 6ltrs a minute on the cold water in. Is that too low?

Do I need to get an engineer in to get the crap out of the plate thing?

I'm quite technically minded.

 

[Agile]

The pressure is a common problem that any competent engineer will understand and know what to do.

I dont think the other issue is the plate HE.

But whatever it is it needs a competent engineer to monitor the boiler as the fault occurs.

We cannot do that on the internet.

Tony

 

[wkdmarty]

That's the problem, I've had 4 engineer visits in the last 2 years and NONE have fixed the problem.

 

[wkdmarty]

That said, I don't mind paying, if it actually fixes the problem. What I hate is when I get charged and the engineers are guessing.

 

[Agile]

That's the problem, I've had 4 engineer visits in the last 2 years and NONE have fixed the problem.

But I would say that you do mind paying! You have already implied that the Worcester price of £300 was expensive. You then say that they are "less than helpful" when you have apparently not called them to fix it.

Instead you seem to have tried one of those insurance type deals where they provide a budget service but cannot afford to employ very good engineers.

Having said that if you keep complaining to them then eventually they would probably fix the problem or call in a Worcester staff engineer who are paid a reasonable salary.

What was your impresssion of the four engineers you had visiting so far?

Tony

 

[wkdmarty]

3 didn't seem to know anything. In fact, it took "a senior engineer" to come out on one occasion and sort the issue, but even that was a temporary fix, as I still have the issue.

I don't mind paying £300 to Worcester, but they don't guarantee to fix it for that price. What I don't want to do is get a guy out who says "it's this" bills me, replaces it, same problem (or same problem 3 months later), then comes out again, another part, bills me, etc, etc.

THAT is the service from 4 "engineers" so far and gladly, I complained and got a refund of my HomeServe Fees

Incidentally, I have had 2 separate companies send engineers out, first was my house insurance because it broke completely. After they went the boiler leaked and short circuited, 5 days later, the senior guy comes out and puts it back to normal. 4 months later, same problem. Hence I asked homeserve to sort it, again no solid fix.

This boiler and the engineers that have been out so far are just a money-pit.

Even here on the forum, one person said "it's the Plate HE" then another posts "no it's not", so it's obviously not as straightforward as it seems.

As I said before, I'm not averse to spending money, but it has to fix the issue or I might as well give it a go myself.

 

[conbow]

No your right, but they will guarantee to fix it for £262.50

 

[slapper]

So I tested the flow, I'm getting a shade under 6ltrs a minute on the cold water in. Is that too low?

Do I need to get an engineer in to get the crap out of the plate thing?

I'm quite technically minded.

If that's 6ltrs cold inlet flow, that seems extremely low, what sort of pressure/flow at the hot taps have you got

What pressure is the incoming cold main to the house, somethings amiss here

 

[wkdmarty]

That's 6ltr/min at the first tap.

My stop valve is 1m from that tap. Hot from same tap is 6ltr/min too.

1.5 bar max pressure too.

Thames water coming out Wednesday to check. Will let you know what they say.

Thank you.

 

[gigz]

Watch the boiler, when you say it goes cold does the green light go out while the hot taps on ?

 

[wkdmarty]

No, the blue light stays on. There's clicking like it's switching something many times.

 

[wkdmarty]

Here's a puzzling thing, just had Thames Water round.

Cold water pipe from ground into stopcock, then within 1mtr goes into boiler, pressure when refilling boiler doesn't go above 1.5 bar.

Kitchen tap is also about 1mtr from stopcock, "cannot test pressure apparently" but flow rate 6ltrs / min being generous.

Outside tap, on the SAME PIPE at kitchen tap a further 1mtr away (stopcock -> pipe -> t to kitchen tap and outside tap) 22ltrs / min and 2.25 bar

Whole house around 6ltrs / min, running off the SAME pipes.

I'm confused as to how this can happen and will that cause the problems in my boiler?

 

[St0rmer66]

You have a blockage of some sort then! Cut out the tee and start looking there. Are there any valves which could be shut or blocked?