unvented cylinder

[southcoastboile]

Customer has asked me to fit a new direct unvented cylinder, he currently has a 125ltr fortic tank. There is only him in the house so he doesnt want to heat water he wont use, he said he occasionaly has people round so would like the same sized cylinder and a plumber friend has told him that.......

If he gets a dual emerssion unvented he can use the top one only for when he is there for shower etc and when he has friends round he can use both. That will be a cheap way of doing it.

Is that true or would it be better using them both at the same time?

I thought it would be better using both as the bottom of the cylinder will not get heated and the top will struggle to reach temprature. Ive given 3 different prices on this job for 3 diff cylinders now but customer is now torn between either a 130ltr unvented with dual emerssion if its cheaper to run one emerssion only and run both emerssions for visitors, or, if not he wants a smaller unvented?

Stupid question I know but I need to quote and give him an answer tomorrow so any advice .. thanks

 

[TBServices]

Technically, as heat rises, the top immersion should heat only the top part of the cylinder, so yes.


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[ahwell]

He can use the top for himself ( less volume of hot required ) then the 2 for more volume of hot water.

 

[Best]

Yes, agree using the top immersion would be better for saving energy when you need just a small amount of hot water, as using the bottom heater will mean it will be a bit slower as the heated water is going through the lower cold water. If the top heater is turned on & left on, the heater stat will cut it off when the water is hot to that higher level, so saving electric.
You only need the bottom heater solely to heat the entire tank, but as Ahwell says, using both heaters would be an option & faster.
Also 2 immersions means you have a backup if one fails, so everyway you benefit.
I think all unvented units should have 2 immersion heaters, if they are to be used.

 

[jtsplumbing]

Will the bottom heater be running of E7 electric ? Why does he want to go over to unvented ?

 

[southcoastboile]

Will the bottom heater be running of E7 electric ? Why does he want to go over to unvented ?

Yeah hes on E7, the hw pressure is rubish due to it being a fortic cylinder.

 

[jtsplumbing]

Have you thought about just fitting a pump on hot water side ??

 

[TBServices]

Have you thought about just fitting a pump on hot water side ??

It's doubtful that the cistern on a fortic will be of a sufficient size to meet the cold water demand if fitting a pump.


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[southcoastboile]

Have you thought about just fitting a pump on hot water side ??

I didnt think about that if Im honest but the customer rang me asking specifically for a quote for an unvented anyway so I just went with that

 

[jtsplumbing]

Well if thats what he wants, why not ! Customer is allways right !! lol

 

[AWheating]

as regards the use of top immersion google hot water cylinder stratification to give you an idea of how a cylinder heats up and has layers of different temps.