Ideal Vogue C32 hot water demand

[luciani]

Hi all, just to say I'm not a heating engineer nor gas safe registered and I am not going to attempt any gas work on the boiler.
We've just had a new ideal vogue c32 commissioned. Noticed today that the boiler fires when cold water taps are used. Even the outside tap which is just after main stop valve on incoming cold supply and some way from boiler. The heating engineer suggested it might be crossed pipes - closing off the cold feed to the boiler and then opening all the hot taps we found there was no hot so we assume it isn't crossed pipes. The cold sink tap (much nearer boiler) also makes the boiler fire - but in each case the boiler only heats a small amount of hot water which feeds into the dhw outlet from boiler before shutting down. If I'm allowed to ask for advice does anyone have any thoughts as to what the problem might be? Could it be down to system design? Thank you

 

[PlumbBobBob]

sounds to me that it has been piped up incorrectly. did you have this problem with your old boiler? or was it a conversion to combi system

 

[luciani]

Hi Steve. Thank you. The house has been refurbished and the plumbing has been replaced completely.

 

[Scott_D]

Got a water meter?

 

[Crinkmeister]

Has somebody connected a hot to a cold somewhere? Turn boiler off, isolate hot water outlet on boiler and turn on hot tap and see if cold water comes out. If so, call chap who installed it back to fix!!

 

[PhoenixServices]

If it's not a crossed pipe it may need a shock arrester on the cold pipe to the boiler. Can sometimes fool the boiler to fire when it sends shock waves down the plumbing.

 

[luciani]

Thanks Scott and Phoenix services.
We don't have a water meter Scott.
Phoenix Services we did try that and with the cold supply to the boiler isolated there was no hot water at any of the hot outlets. Is there any other way to check for crossed pipes or does that prove it Is not crossed pipes?
Thank you.

 

[luciani]

Sorry Phoenix it was Crinkmeister who asked about that. The shock arrester is a good thought. The pipe work is plumbed in such a way that the cold supply to the boiler enters at a T and then feeds the sink. The incoming main and outside tap are one side of the T maybe 3 meters away in pipe length. The sink tap is at the other end of the T. This may not be unusual and apologies if it's completely irrelevant!

 

[Scott_D]

Can you post some pictures?

 

[luciani]

Hi Scott. Sorry I can't do any pictures until tomorrow evening. But I will do then. Thanks.

 

[julesverne]

By any chance was your old system setup an heat only boiler and hot water cylinder. As opposed to the combi boiler you now have.

If so there will be a long dead leg somewhere(prob in the cylinder cupboard).

 

[luciani]

Hi Jules. The house has been re plumbed completely so all new. Previous boiler was also a combi. Thanks.

 

[luciani]

I had a look at the shock arresters that Phoenix suggested and I can see how these would work - a bit like a mini expansion vessel? That could help alleviate the problem absorbing the pressure waves that trigger the boiler? It is activated by closing cold taps as well as opening them but shuts down in between. Would a pressure reducing valve on the cold supply (not on boiler system) help in any way?

 

[Allgoode]

Hi,

Could possibly be cross flow on a mixer tap. Some of the cheaper one's don't have check valves.

May be worth going around house and checking any taps that have isolator valves.

Shut off all the hot feeds to the taps at the isolators and then try turning on the cold tap to test if cross flow has occurred.

If all the hot tap supplies are fully isolated/closed then that would eliminate that possibility.

There are a couple of bits inside the boiler that detect flow/pressure drop but you would need a GSR engineer to investigate further.

One other possibility that you could check if you read the manual is to see if pre-heat is switched on.

This would periodically fire the boiler up to reduce time taken to deliver hot water to the taps.

If you still have no joy then you will need to get the GSR engineer/company that fitted the boiler back to investigate further.

They may need to contact Ideal tech support for guidance but that is there domain and does not need to concern you,

Hope this helps,

Thanks,

Andy

 

[luciani]

Thanks Andy. There aren't any mixers and I think we've established the pipes aren't crossed by shutting off the cold feed at the boiler and checking there was no flow at any of the hot taps. What you say makes sense. Thank you. i think that may well be what I will need to do. I will try to put a picture on tomorrow. Meanwhile thanks to you and to everyone who's taken the time and trouble to post replies. I really appreciate it. What a wealth of knowledge there is out there!

 

[luciani]

Thanks Andy. Sorry I forgot to add we'd tried the pre-heat thing and pre heat is definitely off. I think it may end up going to ideal for guidance as you suggest. Many thanks for your help. I will put a picture on tomorrow in case that throws anything up. Thanks very much to everyone who's taken the time and trouble to reply. I appreciate your time. What a wealth of knowledge out there!

 

[jtsplumbing]

From what you are describing it sounds like you have high cold water pressure, if this is the case you will need to fit a pressure reducing valve & a shock arrester, max water pressure for boiler will be given in the installation instructions.

 

[luciani]

 

[luciani]

 

[luciani]

 

[luciani]

 

[luciani]

As Scott requested here are some photos. Final picture is of incoming main, stop tap and shortly after the outside tap T's off thru the wall. The boiler is located on the opposite wall about 2.5 metres away, around 3.7m of pipe from this point to boiler. When outside tap is opened boiler fires and then shuts down after a few seconds. When tap is closed boiler fires again for a few seconds before shutting down.

 

[harrygashull]

I think Ideal Insist on having a mini expansion fitted to these anyway if I remember correctly...

If you isolate the cold mains going into the boiler and water still comes out of the hot taps then you have a problem.

If the water coming out of the hot taps is luke warm/tepid then the likelihood is that you have crossed pipes.

If the boiler fires up when cold mains is run and then shuts off then it would be advisable to fit a non return valve to the cold inlet to the boiler and also a mini expansion + pressure reducing valve.

After this then an inspection of the hot and cold pipework would be needed to make sure there are no long dead legs in pipework.

 

[luciani]

Thanks Harry. That's very helpful. When you say a non return valve is that a flap valve?

 

[stevetheplumber]

no you get sprung loaded ones now but in my experience use a 22mm one with reducers less likley to stick