Mersey Medway- water heater-cold in morning, hot at night!

[m.a.canavan]

Hello everyone. This is the first time I have posted here. I am not a plumber and perhaps I don't have the language to explain the fault I am having. In the morning (especialy winter ones) the hot water boiler can't seem to heat the water. The pilot is on...the boiler 'fires up' when i turn on the tap...but alas , at best, i get lukewarm. In the past this used to happen on extremely cold days..and I figured that perhaps it was a simple case of the bolier not being good enough for the job. However, recently i have noticed that the gas flame in the bolier (once fired) is only about an inch or so in the morning (a weak flame, if you know what I mean), but in the evening the flame is defintely much bigger and I do get lovely hot water.

Please could someone help me with this problem, or at least point me in the right direction. I would simply pay for someone to check the bolier but I amm absolutely skint at the moment - many thanks in advance.
Mick

 

[chrishutt]

Probably a failing diaphragm. Cheap spare easy to replace.

 

[ChrisR]

Make sure you get the model right though - there's no such thing as a Mersey Medway! All the diaphragms are different, "Super" on the end of the name means it's different too.

 

[m.a.canavan]

Chris Hutt and Chris R - thanks for your input. Chris Hutt - when you say cheap and easy to replace am I right in thinking that only a qualified engineer can do it? Or is it so easy that I could? I am ok with my hands etc but wouldn't by any stretch of the imagination pretend to be an engineer!

Cheers, Mick

 

[ChrisR]

YOu need to be handy with a screwdriver/small spanner, things which don''t want to come apart/go together, and might leak or stick. And it'll make a puddle on the floor.

You don't really need to be Corgi reg to work on your own boiler, but if you don't know how it works, forget it and call someone in.

 

[m.a.canavan]

thanks Chris R - just want to clarify something. Why is it that the boiler weorkd ok in the evening (honest) but not the morning.....in laymans terms what does the diaphragm do?

Cheers, Mick

 

[ChrisR]

Well I work better in the evening than the morning...
Only rationale I can offer is that the water pressure may be worse when everyone is showering in the morning.

Diaphragm is a disc of rubber which moves in response to water flow - venturi effect "sucks" it, if you like. It pushes a plate which pushes a pin which opens the gas valve. If the rubber leaks, the sucking pressure escapes. Does that help!?