DHW Low flow rate from combi

[jgriz]

Hi all,

So another problem with a Wickes Combi 102 / Halstead Ace High...

Boiler is running generally fine, CH works no problem as does DHW in normal use. However when running the (thermostatic mixer) shower I get little or no hot.

Testing I've found if you run the cold whilst running the hot, the hot drops off a lot (much more than if you do it the other way around). Hence no hot shower. In fact the shower doesn't even cause the boiler to fire.

- I've checked the flow at the kitchen tap closest to the mains and boiler and I'm getting around 7 litres per minute cold and 5.5 on the hot.

- I replaced the flow limiter and checked the filter, both were fine and it's made no difference.

- The boiler had a new diaphragm on the flow switch a few months ago, as the DHW wasn't working at all. I have notice some DHW leakage into the CH recently.

What are your thoughts on cause? Plate heat exchanger perhaps? Or something else?

Thanks!

 

[jgriz]

I just want to reframe this question a bit.

Before I call out an engineer, is there any way that I can (reasonably) confirm that it's the boiler that's actually the the problem here?

 

[Agile]

DHW leakage into the CH ???

It sounds as if your shower is rather faulty!

But I am not confident at your abilities to repair boilers even if it was faulty!

Tony

 

[jgriz]

Before I call out an engineer, is there any way that I can (reasonably) confirm that it's the boiler that's actually the the problem here?

But I am not confident at your abilities to repair boilers even if it was faulty!

Agreed, I don't want to repair the boiler myself. I also don't want to call out British Gas for a fixed cost boiler repair if the boiler is not actually broken.

By leakage I assume you understand I mean that the rads are getting a little warm when the DHW is run (I didn't really explain that well). This doesn't happen when the shower runs since the shower doesn't draw any hot water...

 

[Agile]

Leakage normally means a movement of water!

What you have is a diverter valve passing heat to the rads when in DHW mode.

A BG fixed price repair is usually more expensive than a local independent unless expensive parts are required.

Tony

 

[jgriz]

Leakage normally means a movement of water!

What you have is a diverter valve passing heat to the rads when in DHW mode.

Strangely it didn't even click until you said that. Makes perfect sense thanks!

I'd much rather go local independent than BG without a doubt but as you said, I was just worried about the cost of parts...

 

[jgriz]

Well finally got around to getting someone in to look at this from a reputable local place.

The engineer looked at the boiler, ran a few taps and came to the same conclusion about replacing the diverter valve. He also said though, he thinks the reason the shower isn't working is due to not enough pressure from the mains.

His advice was to call the water supplier and ask them to increase it. Would they actually do that?

 

[Dan Robinson]

First time for everything i suppose

 

[jgriz]

As I thought, pretty useless. Got a £90 bill for that bit of wisdom.