Power Flushing - is it always worth it?

[Aulus]

After a frustrating 6 weeks of unreliable HW, British Gas have this time not fiddled with my DV microswitch again, but have decided I need a new heat exchanger. My system has always had Fernox protector/silencer, with DS40 descaling every 3-4 years.

Maybe I should have powerflushed? What say the learned?

 

[AlanE]

Maybe I should have powerflushed? What say the learned?

I say take a sample of the water and send it to Fernox, or another company offering to analise heating water, and find out if you need a powerflush.

Could save a lot of money that way.

 

[Blackadder43]

Do you mean you have only been having problems with your Domestic Hot water?
If so the only type of power flush that would help here is one where you connect to the cold mains inlet to the boiler and the hot water outlet from the boiler and circulate around the DHW heat exchanger

A standard power flush does not come into contact with the DHW side of your boiler...

 

[Aulus]

This is what I am thinking. I wasn't there during the BG visit, but am told he reckoned it was 'scaled up' & needs new exchanger. Now the system side AFAIAC has always been protected (I might get a Fernox test anyway to save the aggro of a flush). And if the mains side of the exchanger has furred up, I would surely have a reduced flow & overheated water (?) - which I do not. I simply have unrestricted flow but sporadically the boiler doesn't switch on the water heating.


I can sometimes get it working but no longer risk ghetto showers...

 

[Paul Barker]

there are a lot of other considerations. Is it piped in plastic? even if its barrier it sludges up quickly regardless of chemicals. Is there or has there been any iron pipe? what is the history prior to this boiler was it a big old iron one?

 

[Aulus]

No, twas a brand new installation 13 years ago in an unmodernised house. All copper pipe, except for shower which is plastic, fitted 3 years ago. The wobbly HW problem is the same whether its the shower or the kitchen tap.

I am now thinking it is the DV itself, now the 3rd the boiler's had since new, and/or maybe the pressure differential switch (now on its 2nd).

 

[Blackadder43]

Has the diaphragm been changed in the DHW diverter valve?
If not give it a couple of weeks and you will have no hot water

A power flush will have no effect on your DHW unless you connect as i said in an earlier post

 

[Blackadder43]

You might think about fitting a water softener before the boiler


Just out of curiosity have you plumbed your washing machine in using both the Hot and Cold feeds to the washing machine?

 

[nickso]

what boiler are we talking about?

 

[Aulus]

I think the DV had a new diaphragm at the last fail (2 or 3 years ago). Yes, WM is H&C feed. Oddly that also broke this week, but that's maybe a worn belt, I have yet to pull the thing out.

Boiler is a Turbomax 282E

Well - I just tried it a few differnt things:

With CH off - little nylon arm on right of DV activated the microswitch every time, so I reckon that's OK. But on one go, the pressure diff switch did not move, & no hot water.

With CH on, nylon arm still moving OK, but pressure diff switch is permently up, & HW every time.

Am I confusing myself?!

 

[Blackadder43]

Washing machine connected to hot and cold feeds.
Here is a little tip for you.
Disconnect the HOT feed to your washing machine...
Reason:
You start washing machine on its cycle
Washing machine calls for hot water.
Valve opens and Boiler senses this, flicks its diverter valve to Hot water and starts to fire
Washing machine gets bored waiting for hot water and switches to cold fill, and heats its own water up..

You will be amazed at the amount of times that diverter valve has to change positions to suit your washing machine.
Run it on the cold feed and give your boiler a break..
Replace Diaphragm in existing Diverter valve and o would imagine you will be sorted...
Unless the heat exchanger is scaled up then it will need a manual clean or replacing.....
But i would go for the £15 Diverter valve repair kit first
And take the hot feed off your washing machine....

 

[Aulus]

OK, WM now on cold fill only. Actually the worst offender for stressing the DV is wife & daughter running hot tap in bathroom constantly on & off for mere seconds when brushing teeth or washing hands!

No chance the pressure diff switch is the fault?

 

[Aulus]

My goodness, I think BG got it right! Engineer has just explained that the exchanger is almost certainly sludged up (system side, and not scaled on mains side as I thought he meant) hence water takes long time to warm up & restricted flow is affecting boiler fire up. Presumably an overheat protection.


Thank you to all that have guided me on this journey!



Now got to pay BG £200 for exchanger...

 

[Agile]

It would be cheaper to get an independent who would be prepared to clean your heat exchanger.

However if the system flow switch is not making reliably then it might have other problems or blockages rather than just a blocked plate HE. The diagnostic test for that is a thermal survey.

British Gas dont have a monopoly on boiler repairs ( in spite of what their engineers sometimes seem to think ).

Tony

 

[Aulus]

Thanks all. Adding up a survey, a water test, & an indie to clean it, probably cost the same to just let BG sort it. At least if it still fails I can challenge them for a refund for uneccassary work.

No hot water again today