Decommissioning water tanks

[Ben100]

Hi guys,

 

I'm in the middle of a house conversion/extension and have just removed the old roof. In the loft I've found 2 cold water tanks which I need to move or remove. This will be a temporary (few months) thing as I'll be putting in a new water system with unvented cylinder, UFH, etc.

 

My questions are:

 

1. Why are there 2 water tanks? 1 is for the shower, but I'm not sure on the other. Maybe for the heating?

2. I need to remove these tanks as the are in the way of the new roof. Can I just remove the tanks and plumb them directly to the water mains, but with a pressure reducer installed?

3. Anything else to consider?

 

Cheers,

Ben 

[PeterW]

One will be the heating header tank so unless you replace the boiler with a system/pressurised system then that is still needed

[Ben100]

2 minutes ago, PeterW said:

One will be the heating header tank so unless you replace the boiler with a system/pressurised system then that is still needed

 

Can't I use a pressure reducing valve to bring the mains pressure down to something ok for the boiler? As I said previously, this would be a temporary workaround until I install the new system in a few months. 

[PeterW]

1 minute ago, Ben100 said:

 

Can't I use a pressure reducing valve to bring the mains pressure down to something ok for the boiler? As I said previously, this would be a temporary workaround until I install the new system in a few months. 

 

No because the term for the boiler header tank is an F&E or Feed and Expansion tank. It allows the water in the heating system to expand and contract as it heats and cools. Withouy it, you will either rupture the heat exchanger in the boiler or spring a leak somewhere - or both

[Ben100]

1 minute ago, PeterW said:

 

No because the term for the boiler header tank is an F&E or Feed and Expansion tank. It allows the water in the heating system to expand and contract as it heats and cools. Withouy it, you will either rupture the heat exchanger in the boiler or spring a leak somewhere - or both

 

Aha, yes understood.

 

Is this header tank used for both central heating and hot water supply? I'm wondering if I can remove the tank, turn off the central heating, but keep the hot water supply running?

[Ben100]

So I think I understand better now. I've seen this diagram.

 

Cold water tank should be ok to use a pressure reducing valve, but heating header cannot be removed as it's used for expansion too.

[ProDave]

It is usually possible to convert the central heating circuit to a sealed system with an expansion vessel, though it is not unusual to find a few unknown leaks when you do this.

 

To get rid of the hot water header tank needs an unvented cylinder, again with the correct pressure reducing valves, expansion vessel and safety blow off valves and their drain.

[Temp]

50 minutes ago, Ben100 said:

Cold water tank should be ok to use a pressure reducing valve, but heating header cannot be removed as it's used for expansion too.

 

Deleted

 

I was wrong.

 

Edited June 30, 2020 by Temp