Semi gravity system - layout?

Joined
29 Oct 2008
Messages
433
Reaction score
17
Location
London
Country
United Kingdom
With a semi gravity system (gravity H/W) and pumped heating, and the heating having an anti-gravity valve after the pump, is there 2 vent pipes (1 for H/W and 1 for HTG) and 2 cold feeds?? Usually semi-gravity systems have 4 tapping-boilers don't they??
 
Sponsored Links
Joined
29 Oct 2008
Messages
433
Reaction score
17
Location
London
Country
United Kingdom
ok thanks for that - must be weird seeing 2 vents going over the header tank!!
 
Joined
8 Jan 2005
Messages
19,003
Reaction score
1,568
Location
Bath
Country
United Kingdom
With a semi gravity system (gravity H/W) and pumped heating, and the heating having an anti-gravity valve after the pump, is there 2 vent pipes (1 for H/W and 1 for HTG) and 2 cold feeds?? Usually semi-gravity systems have 4 tapping-boilers don't they??

No, there's only one cold feed and vent pipe on the gravity circuit or direct to the boiler.

Depends the the size of the boiler, larger boilers have 4+ connections, smaller boilers can have 2 with a special pipe arrangement.

All new installs must be fully pump.
 
Sponsored Links
Joined
15 Feb 2008
Messages
894
Reaction score
103
Location
Manchester
Country
United Kingdom
You should also have two tanks one for heatingsystem and one for cold water feed to the hot water cylinder
 
Joined
8 Jan 2005
Messages
19,003
Reaction score
1,568
Location
Bath
Country
United Kingdom
You should also have two tanks one for heatingsystem and one for cold water feed to the hot water cylinder

The OP is talking about the primary water, and not the secondary water.

I think :rolleyes:
 
Joined
29 Oct 2008
Messages
433
Reaction score
17
Location
London
Country
United Kingdom
Thanks for your info.... I guess as long as the anti-gravity valves are after the pump then it would have been fine with only HW on (ie in summertime).

If you replace a HW cylinder or a boiler on a semi gravity system can you still have the HW gravity, and just use a thermo mechanical stat (ie Drayton Tapsat) or do you need a cyl stat and MV ???
 
Joined
8 Jan 2005
Messages
19,003
Reaction score
1,568
Location
Bath
Country
United Kingdom
You can replace a cylinder like for like, if however you replace a boiler the system should be up-graded to fully pumped.

There's various valves that can be fitted in the primary return circuit, the flow/vent must remain open to atmosphere.
 
Joined
29 Oct 2008
Messages
433
Reaction score
17
Location
London
Country
United Kingdom
I see, a new boiler would mean a cyl stat and a 2port (MV) for the hw circuit as well as the HTG circuit, but a new cylinder only then a tapstat would be allowed.
 
Joined
8 Jan 2005
Messages
19,003
Reaction score
1,568
Location
Bath
Country
United Kingdom
Controls of any sort are always advisable when changing a cylinder, but not, a requirement.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top