Can I have a new combi boiler and keep my hot water cylinder

[blondebier]

Hi Guys,

Still deciding what to do in our "new to us" house...

The boiler is a dog and needs replacing.

Is it possible to have a new combi condensing boiler and retain a hot water cylinder in an airing cupboard?

I'll probably replace the cylinder while I'm at it for a new Heatrae Sadia Megaflo unvented jobby or something similar...

Would a combi work with this or do I need a system boiler?

I really like the sound of these Viessmann boilers, but they don't make system boilers only combis.

What should I do?

Cheers,

Blondebier

 

[doitall]

Yes, you could have the combi feed say the kitchen/utility, and the cylinder/heating on an Y plan.

 

[blondebier]

Thanks DoItAll.

That's great news.

Will the combi heat the hot water on demand like normal and then "push and replace", under the mains pressure, the hot water out of the cylinder? (I hope that makes sense. If not, could you please explain how the hot water would be delivered?)

 

[D_Hailsham]

I really like the sound of these Viessmann boilers, but they don't make system boilers only combis.

That's wrong.

See Viessmann Brochure

 

[blondebier]

Thanks D_Hailsham.

I had a look on their website and couldn't see anything about it... I'll take a closer look!

Maybe an unvented system with a Viessmann boiler and new cylinder is the way to go!

 

[doitall]

A system boiler and unvented cylinder would give you a better hot water supply, provided the mains can deliver.

Get a bucket and time how long it takes to fill and work out how many Ltrs/min it is, then post the answer.

 

[blondebier]

A 12l bucket took 45s to fill from the kitchen tap. So that works out at about 16l per minute.

Is that any good?

 

[doitall]

Not brilliant but probably just about good enough.

 

[mickyg]

i wouldnt install an unvented with less than 20 l/min bit pointless imo

 

[picasso]

I would go for the combi/vented cylinder set up on them figures.

 

[blondebier]

Could you please explain why an unvented system be unsuitable with that flow rate? I'm not really sure how they work.

 

[mickyg]

cos by the time its gone through a load more pipework, controls, valves and a cylinder you could be looking at 12-14 l/min out of your tap. You can get that easily from a normal cylinder or a combi, negating the benefits and costs of an unvented cylinder.

 

[blondebier]

cos by the time its gone through a load more pipework, controls, valves and a cylinder you could be looking at 12-14 l/min out of your tap. You can get that easily from a normal cylinder or a combi, negating the benefits and costs of an unvented cylinder.

Thanks MickyG.

We've had a combi before and were really pleased with it.

We're now in a bigger house though, and I'd rather like to keep a cylinder in the airing cupboard. I also like the peace of mind of having hot water backup in case the boiler were to breakdown.

What's the best way of achieving this?

 

[doitall]

I have to agree with the guys, a small combi serving the kitchen/utility, with the existing cylinder serving the bathrooms on a Y plan.

 

[mysteryman]

Putting in a combi plus a cylinder seems like overkill to me - and you can't have weather compensation.

Just have a system boiler plus cyl, or the floor standing storage combi - which is really a system boiler and unvented cyl combined.