Unvented cylinder running out of hot water

[McNulty]

Hi guys,

got a customer who is running out of hot water with there unvented cylinder when showering.

Basically I fitted a new shower mixer replacing old shower mixer for them and piped it onto there unvented cylinder roughly 150l hot n cold pipes. As before the old shower itself (and only this shower nothing else) was supplied via a huge vented tank in the loft, boosted by a shower pump. Sounds silly and it is, as this vented cylinder was heated 24/7 by 4 x huge elements obviously wasting a lot of electric. Now you can see why they wanted away with the old tank in loft as they have an unvented cylinder already in place feeding the rest of the house, including another shower which they don't use, it made sense to pipe onto that and use the hot water instead of heating this massive tank in the loft.

Now I know the lady who lives there likes a long showers and is used to the old tank, but is there any tips I'm missing on using the hot water up quickly?

Obviously I have told them not to shower as long, but what else can I say? Make sure hot water is stored at correct temp?60c? They have the timer on half hour before usage, should it be earlier? Any advice would be appreciative.

cheers

 

[Millsy 82]

What cylinder is it?

How is it heated? (Immersion/boiler)

What temperature is it at?

How long is it programmed for in total?

What kind of shower is it? (How big is the head?

I can't see it running out unless she is in the for 20-30 minutes or has the water scalding hot! I would say possibly 30 minutes isn't long enough for it to get full up to temperature but depends on the cylinder and how it's heated.

 

[AWheating]

What size is the cylinder?

Are you g3 qualified?

Can you fit flow restrictors in the shower feeds?

 

[Paulus]

It will take more than 30 minutes to heat a tank of cold water. Set temperature to 60 and timer to come on 90 minutes before use. Problem solved.

 

[Megaflo-Experts]

If it's heated by immersion heaters, it may not be reaching full temperature after 30mins!
With 4 immersions in the old vented cylinder, 30 mins may have been long enough, but unless the unvented cylinder also has 4 immersions, I'd say leave it on for 2-3 hrs and then see how it goes. Or you could measure the hot water temperature.

If heated by a gas boiler, 30mins may be sufficient, but I would have it for an hour, at least while investigating the problem.