combi vs open vent

[james7777777]

Hi,

I have made a decision to get my house replumbed and have a new boiler fitted (converting from a one pipe system, open vented system). It's a 5 bedroom house with 2 upstairs bathrooms and a down stairs toilet.

Im not sure what type of system to get - I really like the simplicity of combi boilers after having one in a 2 bed terrace however have been advised they may not be suitable for large houses. Woulbe ne interested on peoples thoughts?

Jim

 

[Roger Welton]

The thing combis struggle with regarding hot water is flow, if more than one outlet is open at once then the temperatre is reduced. (some one will no doubt be alon in a minute to tell you about high output combi's but to me that always seems ligh using a sledgehammer to crack a nut)

I also like having a immersion as a backup in the event of a fault with the boiler. If you can stick with a ovpen vented heating system then the boilers for this are nice a compact with much less to go wrong also.

 

[Nostrum]

I agree with Roger nothing wrong with a correctly piped and sound open vent boiler & system. You could consider an un vented cylinder if your water main is up to it and you want increased flow of hot water, something you almost definitely won't achieve installing a combi over a vented cylinder.

 

[grahamgas]

When you say replumbed, are you upgrading the cold water main?
If you have adeqaute flow and pressure from your incoming cold, and the space to house it then I would be fitting an unvented hot water cylinder and a system boiler.
If space is restricted then keep to an open vented boiler, and add an uvhwc.
Another option would be the glowworm ultrapower. Basically a unvented cylinder with the boiler strapped to the top.

All of this is dependent on your flow and pressure of cold water coming in.

 

[james7777777]

Many thanks gents.

The plan is to have the whole house re piped to convert from a one pipe to a two pipe system. however I have to say if I still have to have a hot water cyclinder, tanks in the loft etc Im tempted to just leave the one pipe system in place, save myself alot of hassle and around £5k and hope a non condensing boiler works ok with my one pipe system when my old netaheat eventually breaks.

 

[Whn1]

Non condensing?

 

[grahamgas]

If you unvenetd then tanks are out of loft, unless you want the loft tank just to feed a toilet etc.
Converting boiler to pressurised system will also do away with f and e tank in loft.
Any new boiler needs to be condensing to comply with building regs.

 

[james7777777]

sorry meant to say condensing. Ive heard they do work with one pipe systems...just

 

[grahamgas]

the ones that I have used on one pipers, have had low loss headers fitted onto the pipe work.

 

[scoullar]

cant beat unvented cylinder with system boiler if you want stored water then fit a break tank and mains pump which grundfoss make