Glowworm 38cxi hot water problem.

[Flamesafe]

Hi everyone,

Im a gas safe registered engineer who is kind of new to the whole gas industry. im having trouble with a boiler and wondering if anyone could throw some suggestions my way, i've got a few ideas but need a second opinion. Basically for example if i run the bath tap and fill up the bath, first nice hot water will come out until the bath is just under halfway full, then it goes real cold and stays that way for about 3 or mins, at times longer, then slowly the hot water will come back, but by the time the bath is full its kinda to cold. The same thing happens in the shower as it is not electric. i thought it may either be the diverter valve or maybe scale build up in the heat exchanger. ive heard about a washer somewhere in this boiler that may need cleaning also. but know no info on this, but i didnt want to check any of these just incase i end up having to replace it and the issue is still there, so thought id ask around on here first.

any ideas anyone? its my girlfriends parents boiler so trying to sort it asap.

looking forward to your replies,

Thanks.

Read more: http://www.ukplumbersforums.co.uk/c...rm-38cxi-how-water-problem.html#ixzz1xEokKFW2

 

[mickyg]

So when it stops running what did you check?

 

[Blueflame786]

Common fault with these is the plate heat exchanger getting blocked .. Either take out and clean or just replace pretty easy to do .

 

[cross thread]

check flow switch , if it fails you get some hot water at first off the pre heat

 

[Whitespirit66]

The washer you may be referring to on these boilers, is the burner door seal. Check to see if it's been changed to graphite one. Should have G10 sticker near the door if been changed.

Some out there still not changed. Had one the other day.

 

[naanbread]

Common fault with these is the plate heat exchanger getting blocked .. Either take out and clean or just replace pretty easy to do .

Wouldnt quite describe this as a "common fault" with the boiler. The boiler is only as good as the quality of the water and system it is on. Not the heatexchangers fault if its scaled.

op. Are you getting any fault codes? I wouldnt say divertor because if that was an issue you would have continuously cooler water, your heating system would also get hot as your calling for a hot water demand.

It does sound like a plate to plate heatexchanger, you could put some temp reading equipment on your flow and return pipes. The difference in temperature between the 2 should stay fairly close together. make sure they arent creeping apart after longer periods of time. You would notice a lot of heat on the flow pipe (maybe getting towards 80/90 degrees) and a cold return (below 50 degrees). Keep your eyes peeled for the F14/F5 fault on hot water only, these also indicate a blocked plate.

Hope this helps

NB

 

[naanbread]

check flow switch , if it fails you get some hot water at first off the pre heat

Flow sensor in these isnt it?

simple check to prove. turn heating on and you get temperature on the display. then turn a tap on and it should show pressure. (leave heating on whilst you do this as HW is a priority) if it doesnt change to pressure you could have a sensor problem (old friend told me that one). GW technial always seem to be good for help with these things when im stuck. they know all the voltages etc.

NB

 

[Emma Harper]

I have just discovered the solution to the exact problem you reported! We experienced the same issues with running a bath/shower etc...
Firstly we turned down our main stop cock as there was too much pressure, also reduce the pressure of the water coming out the taps by turning the tap down 50%. This helped a little but still frustrated as although our baths were hot they took ages to fill!
The stop cock attached to the pipes integrating from the boiler had been knocked by something I had stored in the cupboard, once this was opened fully immediately the water came gushing in & the pressure rose greatly.
Only my experience but I thought it's worth mentioning.