Getting new boiler, should I change the hot water cylinder?

[tangjo]

I've had several quotes in for changing my boiler to take advantage of the boiler scrappage scheme. Two of them said I had to change my hot water cylinder as it does not meet building regulations. I found out from other plumbers that it is not a legal requirement to change it but the old one is less efficient so it is recommended.

I have one that I reckon is 15 years old, in a yellow foam jacket. Does anyone know what energy saving is expected from changing the cylinder to a Ultracal one that heats up water in 15 mins?

One installer said he has never changed a working one as part of a boiler upgrade and he reckons the efficiency saving in our gas bill will be marginal. Another says they recommend the change and 70-80% of customers do change it. Not sure what to believe, what to do? Anyone that can give advice on this?

 

[muggles]

If it's not leaking, leave it be, the energy saving from changing it will be almost nil over the foam-lagged one you already have, it may reheat faster (and that is reheat, it won't heat from cold in 15 mins) but that's just because it has a larger coil in it than a standard cylinder.

Wait until you actually need a new one then order one with double-thickness lagging if you want to conserve a little energy

 

[Agile]

Because there are many silent people who read these forums to gain information, I try to make my advice as helpful as possible and add additional information. Of course some people will complain about that.

When a boiler is changed, the building regs say that a new cylinder "should" be fitted. That does not mean "must" and in any case nobody polices these things.

The advice that I give to clients is that:-

Latest BLUE cylinders are current and dont need changing.

Recent GREEN cylinders are good and little is gained by changing unless the fastest reheat is essential.

Older yellow cylinders are fairly well insulated but the reheat is rather slow compared with the latest ones.

Copper cylinders with no foam insulation waste heat and have a slow reheat and are best replaced. But thats not essential and it can be done at any time after the boiler is fitted.

Tony

 

[mickyg]

Depends a little on boiler thats being fitted and controls as well. If your having a large output boiler with a limited modulation range you could potentially get problems with cycling if the coil in the cylinder is too small. If you were to have weather comp controls fitted it would be essential to upgrade it but I doubt that as very few people recommend efficient controls!
All in all its not a necessity, I'd normally just give the option and the pros and cons. you pays your money you takes your choice!

 

[Happyplumber]

I totally agree with Mickyg advice,In berkshire we have very hard water and its amazing how much scale builds up inside the cylinder 15 year old cylinders around here will have lost 1/2 of its capacity to scale.I dont know the condition of the water in your area or how the cylinder is in your house the advice would be given and the choice would be entirely your own

 

[D_Hailsham]

When a boiler is changed, the building regs say that a new cylinder "should" be fitted.

I can't find where it says that in any of the documents I have. Could you point me in the right direction please?

 

[tangjo]

Thanks for the advice. I'm getting a Viessmann 100 Vitodens 26kw compact boiler fitted. We have very hard water in the area but I know a water softener was fitted about 3-5 years back but I guess there is still 10 years worth of hard water that has gone through the cylinder.

For info, the building regulations I was referring to is in Building Regulations, Part L - hot water system.

 

[D_Hailsham]

I was actually addressing my question to "Agile", but as you have replied, I must point out that there are two Approved Documents for Part L of the Regulations.

Approved Document L1A applies only to new dwellings. The hot water system has to meet the minimum standard laid down in the Domestic Heating Compliance Guide.

Approved Document L1B applies only to existing buildings, so it is relevant to your situation. There is nothing in L1B which compels or even advises that, when a boiler is replaced, the cylinder should or must be replaced with one meeting current standards. If the cylinder has failed and has to be replaced, the new cylinder has to meet current standards.

 

[Nige F]

There are a lot of "grade 3" cylinders about with - Just scrape through the B.S standard kitemark @ the time -coils that have yellow foam lagging . And there are some First Rate ones that are worth keeping . If there is a label on the foam somewhere ,that will reveal a lot . I like D-Hailsham`s advice .But I like Agile`s advice .There is only 1 way to find out

 

[namsag]

Agile dont get caught up in your colour schemes too much as plumbcentre do fast recovery GREEN foam cylinders as well as BLUE.


D Hailsham does it mention anything in the latest CHESS about upgrading them or is it still as clear as mud.

 

[D_Hailsham]

D Hailsham does it mention anything in the latest CHESS about upgrading them or is it still as clear as mud.

No! But as CHeSS is mainly concerned with new systems, I wouldn't expect it to.

In any case CHeSS is only a guide for installers and specifiers as to what should be done. If you want to have the details you have to read the Domestic Heating Compliance Guide - CHeSS is based on the Guide.

Nowhere in the DHCG does it say that, when a boiler is replaced, the HW cylinder must also be replaced if it does not meet current requirements.

Building Regulations are never retrospective; they only apply when a change is made - e.g when windows or doors are replaced.

 

[mickyg]

lower end on that boiler is 9kw. Unlikely your cylinder is anywhere near there so chance of problems. If you want to "try it and see" approach I would discuss with your installer a price to install a new cylinder "if" required, to save issues later.