I have a Glowworm Ultimate - I have no info about it although the control unit says on it that it's for a 30, 40 50 only so I guess it's one of those. It looks as though it's about 15 years old and seems to perform well.
Can I change the heating system so that it runs off mains pressure water rather than using a header tank? ie is the boiler capable of supporting mains pressure?
Thanks

Paul, December 2008

Thanks for your responses - all make a lot of sense. I knew about pressure vessels, it's more about whether the boiler itself would be ok with the pressure but of course it can be at any pressure I set it. Thanks so very much. Maybe I'll leave it till the boiler needs replacing.

Paul, December 2008

When he says supporting mains pressure, hes not on about connecting it to mains pressure all the time. Just using a filling loop like every other sealed system?

Dan, December 2008

As i just said. You dont have to put alot of pressure in the system. You could run it at 0.1 bar which will be far less than what it is now.

Dan, December 2008

I agree with amh but would add that if you connect directly to the mains you're probably contravening some water bye law and more importantly (for you) if something springs a leak you could have quite a flood going on and on and on...until you notice it! If you fit a pressure vessel you have a sealed system with a limited amount of water in it - if something fails it will lose pressure fairly quickly and damage will be limited.

Richard, December 2008

Few things you've missed out.

- Pressure in current system isnt atmospheric, it depends how high the header tank is. 1 bar for every 10m of head.

- The boiler needs to have an overheat stat on it as a safety device so if the boiler stat fails, it will shut off rather than boil.

- The system doesnt have to be at 1 - 1.5 bar, if you want you can run it with as little pressure in as you want.

Dan, December 2008

at the age the boiler is i would be wary you need to get a pressure vessel and safety valve etc .the system at the moment is at about .09 bar. ie one atmosphere if you pressurise it it will be 1.0 to 1.5 bar cold and 1.5 to 2 bar hot, the safety valve realeses at 3 bar so you can understand why the bioler exchanger might fail.
you woul be beter off getting a new system only boiler fitted

amh, December 2008