Worcester Bosch 38CDi GreenStar Water Pressure

[S R]

We've had our WB 38CDi GreenStar boiler for about 6 years.

In th elast few months it has developed the folloiwng faults:

1. Hot water not very hot
2. Heaters not very hot.

A local engineer said the issue was a badly clogged up heat exchanger, but rather than fix/replace that he quoted me a new boiler.

Another engineer suggested the plate exchanger, which was replaced but theer was no real difference.

The last few weeks, we have started to get a sudden drop in pressure (hot and cold) after about 1 minute. The pressure is good for teh first minute, then suddenly drops.

A complication here is that we have have one of those hot water tanks with immersion heater. After the failed attempt at fixing teh boiler we switched to teh tank to at least have hot water.

We normally switch to this during teh winter to stop teh house getting cold when someone uses teh hot water. But we've switched to that now as it is the only way to get hot water.

The pressure probelm is the same even when we shut (swith off and close teh valve to the tank) thyis down.

As I said it was all fine for 6 or so years but now we have these issues.

I am inclined to think this is boiler related and not something with the back poressure or pipes.

We are unmetred.

[Tim+]

If WB are anything like Vaillant interns of after-care, call them, not your local cowboys. They may offer fixed price repairs/service and hopefully will know what they?re doing.

Tim

[newshound]

+1.

Sounds like maybe more than one problem? WB do have a reasonable reputation for reliability.I *assume* you have checked the pressure gauge and that is OK? Do you know if there is corrosion inhibitor in the system? Was it a replacement boiler on an older set of radiators?

[John Rumm]

Well that is could fit in with low output generally. Replacing a main heat exchanger could cost a significant proportion of the cost of the boiler. So if there are doubts about other parts of the boiler, replacement could make sense.

Is this on all taps?

There is something a bit odd here - system configuration wise. You have what appears to be a Combination boiler - i.e. one that can heat domestic hot water directly as well as run the heating, but you also have a hot water cylinder.

This is not an impossible setup, but it is a bit unusual. Sometimes this is done with say the DHW from the boiler being directed to a single shower or the kitchen, and then the cylinder HW being used for baths etc.

Do you still get the pressure drop?

What kind of cylinder is this? Conventional vented type with a header tank somewhere? Or an unvented cylinder fed directly from the mains cold water?

I think we need a better understanding of the wholes system configuraton to be able to get further. Like how the DHW of the boiler plays with the cylinder, and what the valve you make reference to on the cylinder is doing.