Hot water going cold

[bindy]

We have had a Viessmann Vitodens 050-w boiler since 2016 and in the last few weeks the hot water keeps running cold, so only geting a 1/4 of a bath before it goes cold again. We don't need to add cold water which is unsual as it's normally red hot.
Any suggestions what could be wrong please. My local plumber who fitted it says it's needs a service. The last one was about 18 months ago.
But just wondereed if it's anything my husband could do to save the £50 fee.

We don't have the central heating on and have a thermostat.
Do we need to up the temperature. Could it be because the weather has gone colder?

 

[ericmark]

I had a problem with mothers combi boiler, a flexible pipe had kinked, seemed to be loads of water flowing, but it turned out not enough to keep boiler powered up. Also with the shower if Eco switched off, then water would start cold get hot then go cold again then go hot. Best with shower if Eco was on.

But that boiler comes as system or combi, you don't say which, I would guess on a lime build up some where, but at £50 for a service what's the problem? Costs about £150 to service my boiler, normally done every other year.

 

[bindy]

Thanks for the reply. £50 is a lot of money if you haven't got it. Not exactly wealthy.
But around here most plumbers charge £40 to £50, maybe cash in hand. £150 seems a lot, never heard anybody pay that before.
I was only asking as it might have been something we could have done, like altering a switch etc so any savings would be good.
Yes it is a combi boiler but the central heating is switched off.

 

[CBW]

It could be a part failure or could just want a service as advised by your plumber. If you’ve had it on the same temperature setting regardless of weather, then I’d say it’s high enough.

 

[Johntheo5]

We have had a Viessmann Vitodens 050-w boiler since 2016 and in the last few weeks the hot water keeps running cold, so only geting a 1/4 of a bath before it goes cold again. We don't need to add cold water which is unsual as it's normally red hot.
Any suggestions what could be wrong please. My local plumber who fitted it says it's needs a service. The last one was about 18 months ago.
But just wondereed if it's anything my husband could do to save the £50 fee.

We don't have the central heating on and have a thermostat.
Do we need to up the temperature. Could it be because the weather has gone colder?

Let the hot waterflow into a container for exactly 30 secs and measure it into a 2 litre milk bottle or whatever then x2 to get the flowrate in LPM

 

[Johntheo5]

Let the hot waterflow into a container for exactly 30 secs and measure it into a 2 litre milk bottle or whatever then x2 to get the flowrate in LPM

What temperature setting is it at and can you measure the flow temperature when hot?

 

[sido48]

I had a similar problem on my combi It was a component that had failed,

 

[bindy]

Thanks for all the replies, the plumber is here now doing a service on it.