Converting from regular to system boiler

Nymbus

I would like to change from a regular boiler to a system boiler. I don’t want a combi, as we have a high demand for water and have two bathrooms. 

We only moved in July and I have no idea when the heating was originally installed but I would not be surprised if it were 70s or 80s. Some of the pipe work runs through a cement floor. 

How high would the risk of a pipe leak from converting to a system boiler with an unvented tank. I don’t really want to keep header tanks, as they scare the life out of me holding so much water in the loft. Any thoughts would be appreciated. One quote told me that they had never experienced a leak but it could happen. The other said it had only happened a few times out of hundreds of conversions. 

Any thoughts would be appreciated. Is this too risky? Should we just chance it? 

Astria

Don't forget that if you convert a regular boiler to a system boiler then you need to make sure that the rest of the system can support the higher pressure requirement of such a system, particularly the radiators.

Are you in a low pressure area? This could also impact such a conversion.

Personally if the system works currently, I'd leave it in place until it breaks down.

Nymbus

How would I know if the system can support the pressure? Plus the boiler is 25 years old and the cylinder been older. It’s expensive to run and the cylinder is not benefiting from modern insulation so it goes cold fast. So at the least a like for like replacement?

MWT

Nymbus said:

I don’t really want to keep header tanks, as they scare the life out of me holding so much water in the loft.

Personally the risks of a leak in old pipework buried in concrete would worry me a lot more than having header tanks in the loft...

Nymbus

MWT said:

Nymbus said:

I don’t really want to keep header tanks, as they scare the life out of me holding so much water in the loft.

Personally the risks of a leak in old pipework buried in concrete would worry me a lot more than having header tanks in the loft...

Yes that’s a fair point. 

Nymbus

So replace with a new regular boiler and cylinder then? 

MWT

Do you feel lucky?

I faced that choice recently and decided to stay with the low pressure system.

It just wasn't worth the risk of needing to bypass all the pipework under concrete on the ground floor, or to disturb all the floor coverings upstairs if something had leaked.

Nymbus

MWT said:

Do you feel lucky?

I faced that choice recently and decided to stay with the low pressure system.

It just wasn't worth the risk of needing to bypass all the pipework under concrete on the ground floor, or to disturb all the floor coverings upstairs if something had leaked.

I think you are right. Did you just replace the regular boiler for another and a new cylinder? 

doodling

Hi,

There seems to be some confusion. Is the OP wanting a sealed CH system or are they wanting a mains pressure hot water system, or both?

The CH header tank doesn't exactly hold a lot of water (usually 5-10 liters) - I'm not sure why that would be scary.

If a CH system cannot stand being converted to a sealed system then it needs fixing anyway. 

Nymbus

doodling said:

Hi,

There seems to be some confusion. Is the OP wanting a sealed CH system or are they wanting a mains pressure hot water system, or both?

The CH header tank doesn't exactly hold a lot of water (usually 5-10 liters) - I'm not sure why that would be scary.

If a CH system cannot stand being converted to a sealed system then it needs fixing anyway. 

What do you mean by “OP”?

MWT

Nymbus said:

MWT said:

Do you feel lucky?

I faced that choice recently and decided to stay with the low pressure system.

It just wasn't worth the risk of needing to bypass all the pipework under concrete on the ground floor, or to disturb all the floor coverings upstairs if something had leaked.

I think you are right. Did you just replace the regular boiler for another and a new cylinder? 

Our cylinder did not need replacing, so it was just a boiler swap for a new vented boiler.

doodling said:

If a CH system cannot stand being converted to a sealed system then it needs fixing anyway. 

Why? .. a low pressure system, often buried under concrete that is giving no cause for concern does not need replacing.

You don't know if you have a problem until you pressurise the old pipes and rads, by which time you may have a problem which wasn't an issue before...