Boiler / hot water cylinder advice

andym5

Hi

I want to fit a new boiler and a non-vented hot water cylinder. I've just had someone round to quote, he is well recommend and actually installed the current boiler in the house 20 years ago (before I owned it). He's recommending I fit a Combi boiler to use with the cylinder. The Boiler would be in the downstairs toilet so he says that tap would be direct off the boiler with all the other outlets off the cylinder. Apparently the Combi would be cheaper than a heat only boiler. I've never heard off this before, is it a sensible way to go? He's suggesting a Baxi boiler, I was going to go for a Worcester but he recons they are not worth the cost, any thoughts?

ic

Get more engineers in to quote and advise.

Johnandabby

Unusual to mix and match combi and cylinder. Combis generally have larger output to heat water instantaneously, and whenever I've looked are more expensive than heat only boilers. I would have thought in most cases a combi would be oversized if your only using it for a single basin.

definitely get other people in to quote - perhaps this guy has a combi in the van he wants to shift...

C_Mababejive

Its an option but really, if you want to retain your cylinder (good idea) then i would be thinking a standard system/heat only boiler. It will be simpler in operation and hopefully a bit cheaper to install?

Edit..having checked boiler prices, for many models there doesnt seem to be too much difference. Maybe the combi could be a look to the future? Of course it depends on your individual hot water demands but if your cylinder packed up,could the combi feed all your HW needs?

andym5

Thanks for the replies. This is the fourth person I've had round. I currently have a conventional system with a vented cylinder. I want an unvented cylinder to improve hot water pressure, mains pressure is good. It's a good size older 4 bed house with a bathroom and en-suite being installed as part of the job. We have two children so I expect quite high demand as they get older. The others have tried to push me towards a Combi boiler but I don't want that, I know it should do the job but it's not really what I want. I thought a combi would be more expensive but thinking about it were not talking about the 42KW one I would have if it was supplying the whole house hot water, it would be the same size as a conventional boiler, probably 25Kw. I'll see when I get the Quote. What size cylinder should I go for, I'm thinking 180l?

C_Mababejive

Whats the existing cylinder like? is it modernish/lagged? Where is the cold water tank? could it be raised to increase head of water?

andym5

C_Mababejive. The existing cylinder is about 20 years old, it is lagged, but only about 100 litres. There's no room to raise the cold water tank. I really want the pressurised hot water tank, I have one in a previous house and loved it.

southcoastrgi

180 or 210 ltr, forget the combi idea, nowt wrong with Baxi, forget all the WB hype

fezster

A combi doesnt really make sense if you're going to have a hot water cylinder. How would it be piped up ? You cant connect both the combi and the cylinder to your HW outlets. Running a single tap off of the combi seems a waste - why not just pipe it up to the HW cylinder ?

The other thing to consider is that combi boilers are normally oversized for the HW demand, whereas your heating requirement is usually much lower. Obviously depends on how big your house is, how many rads you have, and what your HW requirement is, but having an oversized boiler can present it's own set of problems, as well as being inefficient (ask me, I know !).

The other thing to consider is that if a combi breaks down, you're without heating and HW. With a cylinder, you have an immersion heater to give you hot water using electric power.

I'd stick to a standard system / open vent boiler, and a decent unvented cylinder. Make sure your installer is G3 certified, as well as gas safe registered, as you need this to sign off on an unvented installation.

SuzieSue

I've been looking in to doing the same to replace a Baxi Powermax HE150 which has a boiler and unvented hot water cylinder all in a single unit and came across this from Valiant:

http://www.vaillant.co.uk/products/domestic-boilers/system-boilers/

I don't really know anything about heating systems, but it seems that this option allows you to have a boiler with a megaflow hot water cylinder.

Owain_Moneysaver

It can be sensible to have a combi + cylinder combination, but usually where the cylinder is vented, and mains pressure is also needed for a shower.

I wouldn't see much advantage to using the combi hot water in a toilet, unless it's a long way from the cylinder and the combi would give quicker hot water for hand-washing.

Combis are very price-competitive, but they are more complicated than system boilers and may be less reliable.