CH but no HW

[VWFreak]

ok having a problem with my combi boiler, its a worcester 28si.. basicaly the heating side of things is working but the hot water isnt, when i turn any hot tap on in the house there is very little pressure (seems to have suddenly gone bad) and it doesn't trigger the flow switch in the boiler to fire up the gas...(if i manually flick the micro switch the gas fires) i origionaly thought that maby there was a blockage in the flow switch or that the diafragm had split and had maby blocked something but i took it apart and it seems clean and working, the next thing is the coiled pipework that gets heated by the gas...(the heat exchanger i guess) is this likley to be blocked?? or is there filters in it at all??
any pointers greatly receved!! also the pressure of cold feed to the boiler seems to be good

 

[namsag]

There is a filter/ flow restrictor fitted in the inlet of the water flow turbine. Explains how to remove it in installation instuctions

 

[VWFreak]

There is a filter/ flow restrictor fitted in the inlet of the water flow turbine. Explains how to remove it in installation instuctions

hi do you mean the filter in the body of the flow switch housing/valve?? if so i have checked that one and its clean?

 

[Agile]

There is a filter/ flow restrictor fitted in the inlet of the water flow turbine. Explains how to remove it in installation instuctions

I think this one has a conventional diverter valve!

Worcesters are not Vaillant 824s you know ( or dont! ).

Or am I making a fatal mistake? If so then I can blame it on the Kingklip!

 

[kevplumb]

origionaly thought that maby there was a blockage in the flow switch or that the diafragm had split and had maby blocked something but i took it apart and it seems clean and working,

after you had the flow switch to pieces did you adjust the flowrate with the red knob

 

[namsag]

Agile worcester 28si ll installation and sevicing instructions figure fifty six section fifteen.nine explains how to remove and clean the filter from the FLOW TURBINE. there terminology not mine and it looks nothing like a divertor valve.

I have given instructions for 28si ll as there is no 28si on worcester web site in present or discontinued list there is a 28i but that was a different series of boiler

 

[VWFreak]

Agile worcester 28si ll installation and sevicing instructions figure fifty six section fifteen.nine explains how to remove and clean the filter from the FLOW TURBINE. there terminology not mine and it looks nothing like a divertor valve.

I have given instructions for 28si ll as there is no 28si on worcester web site in present or discontinued list there is a 28i but that was a different series of boiler

sorry yes your right the "flow turbine" is nothing like a divertor valve its a white plastic box with a filter on the inlet pipe and a flow adjuster on it, i have cleaned it out but im wondering iff the flow adjuster maby faulty as if i turn it in or out and adjusts nothing!
ill pull it apart again...

 

[namsag]

Well Agile it looks like yet again i know what i am talking about where as yet again you are talking shi#e. Or is it someone elses fault.

Vwfreak is there enough play on the cold pipe just as it enters boiler to rig something up to check flow an see if blockage is before the boiler

 

[kevplumb]

yet again you are talking shi#e. Or is it someone elses fault

its your fault for being a clever shi#e

 

[namsag]

Kev wish i was clever enough to do those wee moving pictures.

 

[VWFreak]

Well Agile it looks like yet again i know what i am talking about where as yet again you are talking shi#e. Or is it someone elses fault.

Vwfreak is there enough play on the cold pipe just as it enters boiler to rig something up to check flow an see if blockage is before the boiler

yea will try that, but on the cold feed there is a sink "T'd" off the same pipe just before the boiler connection and the pressure to that seems very good but i will check and report back! thanks for all the help so far!

 

[namsag]

VWFreak looking at manufacturers flow diagram the only things on HW circuit is the flow turbine and the bi flow heat exhanger .The chance of heat exchanger being bloked is very very remote . A few boilers in the past have had these and i have never seen one block.

So providing pressure to boiler is ok and nothing has blocked the appliance isolating valve front of which can be removed to look and check inside. It is looking like flow turbine..

With the turbine removed and the electics covered could a hose be held into connection to check flow up to that point and then coonect hose to mains and check flow through heat exchanger to taps

 

[VWFreak]

The chance of heat exchanger being bloked is very very remote . A few boilers in the past have had these and i have never seen one block.

many many thanks for the reply and looking it up for me... but a blocked exchanger looks exactly what it is i took the pipe off the inlet side of the exchanger and tyrned on the cold feed ad "woooosh" loads of pressure! re connected and disconnected the pipe from the outlet side of the exchanger put my hose on the end and just a trickle.... so looks like its a new exchanger for me im guessing that this is going to set me back a couple of hundred sqid for a replacement as i guess there un serviceable..
how can i stop this happening again and what could have blocked it up as theres a filter in the "flow turbine"...

thanks again for all your advise....

 

[Agile]

I have come across a Worcester 28i boiler with lime scaled biflow HEs in the London area where scaling is no problem normally.

The first time there was some flow and I managed to clear it with sulphamic acid and the power flushing pump.

The second time it was blocked completely and 32% HCl at both sides failed completely!

Tony

 

[ChrisR]

I've had a couple too.
VWF do you have hard water? Problem accelerates once the flow is reduced a bit, as the water gets over the magic 60 something when it gets limescale depositing.

Hozelock garden sprayer (£20) has 8mm outlet pipe which you can use standard plumbing adaptors on to get to 1/2" so you can fit your boiler connection pipe (the one on the turbine). They state that they pump to 3 bar. Sulphamic acid is probably best (Fernox DS-3) but many kettle descaling products would work too.
Collect what comes out of the hot tap and send it round again. Turn boiler on just enough to warm it up!

A WB Junior in Epsom (water is ultra hard) scaled solid in 4 months. WB exchanged heat exchanger under warranty(!) and insisted user fit a combi-mate. 6 months later it was blocked again.