Boiler advice

330d

To follow up on this;

I thought the boiler in our new house was a system but in fact its a Regular boiler - Worcester Bosch Greenstar 15Ri. I assumed the water tank in the loft was no longer connected but I am guessing it is as I have a regular boiler?
The water cylinder is 117l indirect.



What I am confused about is if the water tank in the loft is being used or not? I ask because I believe systems that use the water tank are vented systems. But I have a separate expansion vessel which is what unvented systems use!

So my question is, how do i determine if the water tank is being used or if the boiler is using the mains water pipe?

Jeepers_Creepers

Oh bless your innocent cotton plumbing socks :-)

Congrats - you DO have a 'system' boiler and you DO have a vented system :-)   

The boiler is 'system' - ie it is sealed/unvented along with the radiators, has a pressure gauge and an expansion vessel. It therefore does NOT have a wee 'header' tank in the loft.

Your hot water system is 'vented', ie open to atmospheric pressure. It is not 'sealed', but is being supplied by the large CWS tank in the loft which provides it with its cold water supply, driven by the 'head' or height of this tank above the hot cylinder - the higher that tank is, the better the hot flow (and cold too, except for the kitchen tap). This part of your system does not need an expansion vessel to accommodate expanding hot water since it simply pushes excess water back up in to the cold tank.

You have a shower booster pump there - these can only be used on 'vented' systems like this.

330d

Jeepers_Creepers said:

Oh bless your innocent cotton plumbing socks :-)

Congrats - you DO have a 'system' boiler and you DO have a vented system :-)   

The boiler is 'system' - ie it is sealed/unvented along with the radiators, has a pressure gauge and an expansion vessel. It therefore does NOT have a wee 'header' tank in the loft.

Your hot water system is 'vented', ie open to atmospheric pressure. It is not 'sealed', but is being supplied by the large CWS tank in the loft which provides it with its cold water supply, driven by the 'head' or height of this tank above the hot cylinder - the higher that tank is, the better the hot flow (and cold too, except for the kitchen tap). This part of your system does not need an expansion vessel to accommodate expanding hot water since it simply pushes excess water back up in to the cold tank.

You have a shower booster pump there - these can only be used on 'vented' systems like this.

Are you sure its system?? The models is Worcester Bosch Greenstar 15Ri which is believe is Regular.

Jeepers_Creepers

Hmm, my apologies - it does indeed say 'regular'. Does yours have a pressure gauge on the front?

Jeepers_Creepers

What does the gauge on that red EV read? I wonder if someone has converted it from 'regular' (vented) to sealed 'system'?

fezster

A "system boiler" has the EV built in. A regular "heat only boiler" can be used in both an open vented and sealed system.
In OP's case, he has a regular boiler, with a separate red EV to make it a sealed system.

The tank is a normal vented one, with a cold water storage tank in the loft. This can have a pump added to boost the water pressure until the tank is depleted. An unvented cylinder works directly off of the mains.

330d

fezster said:

A "system boiler" has the EV built in. A regular "heat only boiler" can be used in both an open vented and sealed system.
In OP's case, he has a regular boiler, with a separate red EV to make it a sealed system.

The tank is a normal vented one, with a cold water storage tank in the loft. This can have a pump added to boost the water pressure until the tank is depleted. An unvented cylinder works directly off of the mains.

Thank you for the clarification.

To go back to my original question, I want to move the boiler and hot water cylinder to the loft. Obviously this is not going to work now as the tank needs to be higher than the boiler.

So the only option I can see now is to remove the water tank and fit a system boiler. Is there any issues with this? What am I loosing going to a system boiler setup?

fezster

A system boiler will add nothing to what you already have (unless you meant combi?) 

Hot water tank in loft is problematic because it ideally needs to be located below the cold water storage tank. 

Why not remove the CWS and HW tanks and just have an unvented cylinder installed in the loft? 

330d

No I did mean a system boiler.

I was thinking of removing the CWS and getting a system boiler in the loft.

I believe a combi will not work well for us as we have two mixer showers and want good pressure.

fezster

A system boiler will give you nothing on top of the boiler you already have, set up for a sealed system. 

You're right, for 2 mixer showers, I'd go unvented, provided your incoming water main is sufficient (preferably 2-3 bar min and 20-30 l/min flow).