Advice for New Glow worm boiler please ..

ohbrother · 28-04-2010, 18:23

We just had a new glow worm combi-boiler fitted, but having never had a combi before, we are unsure if it is working properly. It gives lovely hot water on demand, which is great. But it seems to "fire up" whenever we have used cold water too(you can hear it humming and a couple of pipes running from it get hot)! Just for a minute after using any cold water in the house inc. cold feed washing machine, flushing toilet, running cold tap, ect.
We cannot understand why it would need to function at all after only using cold water, and are worried about un nessesary gas consumption.
Just hoping someone on here might be able to shed some light??
xx

speedfreak · 28-04-2010, 18:32

I might be able to help. Is the boiler model a cxi? If not what is it?

Just a thought, have you had the installers back?

ohbrother · 28-04-2010, 18:34

hi yes its a 38 cxi

speedfreak · 28-04-2010, 18:40

Just incase its a coincidence with the cold water, on the front of the boiler theres a picture of a tap next to a control knob, from fully anti clockwise it starts with a black line, after that its a solid red block, that turns pre heat on/off, try turning that hot water control knob down so its within the black line, if that doesnt make sense let me know and I'll try and show you a picture

ohbrother · 28-04-2010, 18:48

* no, not had installers back yet, thought wed check on here to see if we were just being abit neurotic

---------- Post added at 17:43 ---------- Previous post was at 17:41 ----------

will go have a look. brb

---------- Post added at 17:48 ---------- Previous post was at 17:43 ----------

no that doesnt really make sense with what we can see. If its not too much trouble, a pic would be great

speedfreak · 28-04-2010, 18:52

Did they leave you a book, I need the G.C number it will start 47, something like 47-014-37

Are you having other work done, e.g are there any pipes to taps etc that have been disconnected and capped off?

For now, there should be 3 knobs on the front, an on/off switch, a HW control knob and a central heating control knob, try turning the Hot Water one to off and see if it does it

ohbrother · 28-04-2010, 18:54

yes its 47-019-03

speedfreak · 28-04-2010, 18:58

scrap what I said then its a different model, I'll post back when I've figured it out

an answer on the pipework etc is needed though

ohbrother · 28-04-2010, 19:04

Ok I switched it to off, like you said then put cold water tap on and off and it doesnt do it.

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No other works have been done, no capping off that we know of. Just the old back boiler and tank taken out and the new combi put in..

speedfreak · 28-04-2010, 19:16

If I was you I'd get the installers back, its really hard to diagnose something like that over the internet without seeing it but after looking at the boiler on my work laptop its more than likely being caused by a "deadleg", a redundant piece of pipework on the system with air trapped inside it. Without going into detail it can cause back pressure and when you run cold water/mainly when its ran and then shut off, it can "make" the hot water flow switch so the boiler thinks you have opened a hot tap. Its either that or the hot water just preheating but if its definitely only doing it after using the cold then get the installers back. Hope that helps, not much more I can do from the other side of a computer screen

Around where they have removed the old cylinder may offer a clue to the installers. Its nothing to worry about by the way and wont cause any damage but better to get it sorted whilst you can still get them back to it

ohbrother · 28-04-2010, 19:19

Ok thanks ever so much for the advise. Shall get installer onto it asap, but glad now we know that its a fault.

speedfreak · 28-04-2010, 19:22

Quote:

Originally Posted by ohbrother

Ok thanks ever so much for the advise. Shall get installer onto it asap, but glad now we know that its a fault.

No problem just wish I could help you more! Yes if its doing it whenever you have used the cold its a fault, dont be fobbed off and just to reassure you, as I said its perfectly fine to use so shower to your hearts content

Welcome to the forum by the way