Regular gas boiler with unvented cylinder.

[scotview]

We currently have a small 15kW, regular (vented) gas boiler and vented cylinder, with a cold water header tank (30 years old) and a small header tank for the boiler. The small boiler has very good turndown efficiency with our zone heating system.

I am keen to have the house hot and cold water fed from the mains. This will ensure that all our water system is effectively fed from fresh mains water and at mains pressure. We could also do away with our shower pump. This would be achieved by installing an unvented cylinder. Modern unvented cylinders are also highly insulated.

Has anyone experience of matching a regular boiler with an unvented cylinder. Would this mean that the cold water header tank could be removed but the small boiler header tank would still need to be retained ?

I am not keen on fitting a system boiler due to complexity and putting mains pressure onto our 30 year old central heating system.

Hope you understand the query. Thanks in advance.

[Mike4]

Has anyone experience of matching a regular boiler with an unvented cylinder. Would this mean that the cold water header tank could be removed but the small boiler header tank would still need to be retained ?

I have experience here.

Yes you're right, an open vented boiler can be easily connected to heat an unvented cylinder using much the same controls as it is probably connected with to your vented cylinder. The small header tank would need to be retained.

There is no need to convert the boiler and heating system to sealed/unvented. In fact you probably can't anyway, unless your boiler has an integrated overheat protection thermostat.

[scotview]

Has anyone experience of matching a regular boiler with an unvented cylinder. Would this mean that the cold water header tank could be removed but the small boiler header tank would still need to be retained ?

I have experience here.

Yes you're right, an open vented boiler can be easily connected to heat an unvented cylinder using much the same controls as it is probably connected with to your vented cylinder. The small header tank would need to be retained.

Brilliant ! Thanks for the quick answer. One other reason for the upgrade is that our grand daughter has cystic fibrosis and when she stays with us I get anxious when she uses our cold water tank fed showers.

Thanks.

[Mike4]

Has anyone experience of matching a regular boiler with an unvented cylinder. Would this mean that the cold water header tank could be removed but the small boiler header tank would still need to be retained ?

I have experience here.

Yes you're right, an open vented boiler can be easily connected to heat an unvented cylinder using much the same controls as it is probably connected with to your vented cylinder. The small header tank would need to be retained.

Brilliant ! Thanks for the quick answer. One other reason for the upgrade is that our grand daughter has cystic fibrosis and when she stays with us I get anxious when she uses our cold water tank fed showers.

Thanks.

Not sure I understand the connection. Do you worry about Legionella perhaps?

One downside to an unvented cylinder is no tankful of water stored in the loft. If the mains water supply gets turned off by the water authority for any reason, you have no water at all. Toilets won't flush in particular.

[scotview]

Not sure I understand the connection. Do you worry about Legionella perhaps?

The cylinder stat is set to 60 deg so legionella isn't an issue. But our taps, including the cold shower feeds are from the cold water tank. The only fresh cold water is the kitchen tap.

Putting everything onto a mains supply would just give me a little bit more confidence.

My wife does like the idea of having a store of water in the header tank.

We'll need to give it a bit more thought. Thanks for your very useful feedback.

[Mike4]

Not sure I understand the connection. Do you worry about Legionella perhaps?

The cylinder stat is set to 60 deg so legionella isn't an issue. But our taps, including the cold shower feeds are from the cold water tank. The only fresh cold water is the kitchen tap.

Putting everything onto a mains supply would just give me a little bit more confidence.

My wife does like the idea of having a store of water in the header tank.

We'll need to give it a bit more thought. Thanks for your very useful feedback.

You're welcome.

Still not sure what it is that troubles you about water being stored in a tank. But maybe the reason doesn't matter. If it bothers you, then it bothers you and no amount of 'facts' will stop the niggling doubt.

You could have the basin taps on mains water and keep the tank to fill the toilets, which might alleviate your wife's concerns.

[88V8]

Not sure I understand the connection. Do you worry about Legionella perhaps?

The cylinder stat is set to 60 deg so legionella isn't an issue. But our taps, including the cold shower feeds are from the cold water tank. The only fresh cold water is the kitchen tap.
My wife does like the idea of having a store of water in the header tank.

That is how houses routinely are and have been for yonks.
Ours is, our previous house was and the house before that, going back 45 years.
Our vented cylinder, fitted by me, has pre-applied foam insulation and keeps hot all day.

If you put mains pressure into a system not designed that way, it may become very noisy. Quite apart from losing the water storage.

I too fail to see the connection with ms.

V8

[scotview]

If you put mains pressure into a system not designed that way, it may become very noisy. Quite apart from losing the water storage.

I too fail to see the connection with ms.

V8

Aye, I ken, I ken. I understand all your points but I am just asking the likes of Mike4 to give some feedback on the practicalities. I'm not saying I'm going to do it.

By the way, it isn't MS its CF, cystic fibrosis and anything I can reasonably do to prevent the probability of her coming into contact with contaminated water I'll do. Maybe that's me being pedantic and over reactive but there its is.