Highflow 400 no hot water

[Millsy 82]

I have been to a worcester highflow 400 electronic today which has a problem with hot water. Heating works fine.

Pump starts boiler fires up runs for about 20 secs burner goes off for 20 secs and keeps going like that ( Its got to be a circulation problem) and the radiators start to get warm.

Pump is fine removed diverter all working fine but alot of muck in the system cleaned out a small tube running between DV and the return to the pump. Started looking at the plate but it looks a pig to get out ( Have to remove the flow and return manifolds) and because it was 7.00 and I didnt have any O rings thought it best to leave alone.

Is there an easier way to remove the plate from these boilers without having to remove the flow and return manifolds?

Is there any thing in the flow and return manifolds like Non return valve etc that I should check?

I am pretty certain that its the plate clogged up but could there be anything else I have over looked?

And finally can these boilers be chemically power flushed as that is what it really needs but the last engineer said you cant flush them for some reason and the woman wont listen to me when I say you can. (But I know there are a couple of boilers which didnt react well to cleaner being put in vaillant 828 I think was 1 of them as it swelled the balls in the diverters but they then changed the material of the balls)

 

[GrahamM]

There are filters in manifold and flow switch. Need get yourself MI's and have a good look.
Not the easiest to work on. Hate them!

 

[diamondgas]

They are one of the most complex boilers to work on and giving them a wide berth is one way of sorting it! However if you can't then I'd agree with GrahamM ... Find out where the filter is and check it out! Never had to take the p-hex out as I can count on one hand how many I've seen over the years! Give Worcester a call regarding flushing out but you'll be limited to the effect it'll have by sounds of it! If the custard isn't happy with your recommendations ask them to get Worcester out!!

 

[Millsy 82]

Thanks both of you.

Well I went back out today armed with a bag of O rings and a plate heat ex. Tried to find the filter but couldnt so stripped the boiler to bits and found the filter which was blocked solid cleaned it put the whole boiler back together and hey presto worked brilliantly. Took just over 2 hours and now I know where it is it will only take 10 mins to clean next time (Behind the bypass pipe a 3/4 brass plug it is in there but tricky to get out).

Also spoke to worcester who said these boilers cant be power flushed as it will wreck the diverter valve.

 

[GrahamM]

Glad hear you got it sorted.