bypass gate valve position

[mpullar]

Hi,

my father in law put a screw through a pipe over the weekend and in an effort to stop the water from leaking he turned off all of the valves that he could find in his loft. I went over to help and between us we drained the system and replced the damaged pipe. When we refilled the system we had major problems getting the system to fire up again, presumably as a result of an air lock somewhere. After much muckng about the system now works however I am now unsure of the position that the valve on the bypass loop shuold be in.
The system that he has is a gravity fed open system but whereas many have a three port valve installed he has two, two port valves, one for the heating and the other for the hot water. There is then a length of pipe work that runs from one side of the pump to the other which has what appears to be a gate valve installed on it. I know that this is the bypass just in case both of the valves close, my concern is what position should the gate valve be in? I know that it shouldn't be fully closed as this could cause problems for the pump, and I would think that it shouldn't be fully open as the water will just circulate around this loop. Is it a case of opening this say half a turn to allow some water to bypass but leaving the majority to circulate?
I will admit to being a little surprised to see a gate valve on the bypass as I would have thought that some kind of automatic valve that opened under pressure would have been more suitable.

Any help or advise that you can give would be most appreciated

Thanks

 

[newbie1]

its a bit of a fine balancing act it just need to give a flow path for the water so try it from fully closed crack it back about a half turn and see how it performs

 

[mpullar]

its a bit of a fine balancing act it just need to give a flow path for the water so try it from fully closed crack it back about a half turn and see how it performs

Thats brilliant, thank you.
So it's just a case of opening the valve sufficiently to allow water to pass it in case there are problems but not so much that all the water flows past it and nothing goes round rest of the the system?
I will experiment tonight and see how I get on.
Thank you so much for your help

 

[fuzzy]

Hi,

my father in law put a screw through a pipe over the weekend and in an effort to stop the water from leaking he turned off all of the valves that he could find in his loft. I went over to help and between us we drained the system and replced the damaged pipe. When we refilled the system we had major problems getting the system to fire up again, presumably as a result of an air lock somewhere. After much muckng about the system now works however I am now unsure of the position that the valve on the bypass loop shuold be in.
The system that he has is a gravity fed open system but whereas many have a three port valve installed he has two, two port valves, one for the heating and the other for the hot water. There is then a length of pipe work that runs from one side of the pump to the other which has what appears to be a gate valve installed on it. I know that this is the bypass just in case both of the valves close, my concern is what position should the gate valve be in? I know that it shouldn't be fully closed as this could cause problems for the pump, and I would think that it shouldn't be fully open as the water will just circulate around this loop. Is it a case of opening this say half a turn to allow some water to bypass but leaving the majority to circulate?
I will admit to being a little surprised to see a gate valve on the bypass as I would have thought that some kind of automatic valve that opened under pressure would have been more suitable.

Any help or advise that you can give would be most appreciated

Thanks

have you checked this out allready? you seem to know alot about the system. you also know that it should not be a gate valve on the by pass but a auto bypass valve.
there shouldnt be manual valves on the flow to hot or heating, but since there is whats the prob with keeping by pass gate valve shut? if you shut both gates on flows open the bypass?

 

[mpullar]

have you checked this out allready? you seem to know alot about the system. you also know that it should not be a gate valve on the by pass but a auto bypass valve.
there shouldnt be manual valves on the flow to hot or heating, but since there is whats the prob with keeping by pass gate valve shut? if you shut both gates on flows open the bypass?

Sorry, I shoudl have explained the situation a little better. The two valves that are on the hot water and heating pipes are not manual valves they are controlled by the boiler (they look very similar to three port valves but have only two ports). When the boiler is set to hot water only the heating valve closes and vice versa. On systems where there is a three port valve there is no bypass by on this system with the two, two port valves there is a bypass. Presumably this is there because if one of the valves were to fail in the closed position then the other could close and then that would cause a problem for the pump. With a three port valve if it fails it will block the hot water or the heating but it cannot block both therefore no pypass is required.
The issue is that on the bypass loop there appears to be what looks like a standard gate valve. Although I will admit that I do not know what an automatic bypass valve looks like I woudl have thought that it wouldn't have a handle (although possibly you can get one with shut off?). If this is in fact an auto bypass valve then I just need to open the handle and let the valve do it's job. I think though that it is a standard gate valve and so therefore if I open it then all the water will flow round this loop and the system won't work. Therefore do I just open this a little (as suggested above) or maybe I should replace it for an auto bypass valve? Is there a way to definitively tell from the outside if this is s gate valve or an auto bypass valve?

 

[LIFES A GAS]

Sounds like you have it sorted, If the by-pass is opened too much you might loose circulation on the downstairs radiators as water prefers to take the route of least resistance, by the way most older systems with zone valves had a gate or ball-o-fix type of valve in the bypass so dont worry that its not an automatic bypass, most 3 port valves dont really need a by-pass as there is always an open circuit for the water to circulate but I think the rules state one should be fitted now days, once set it's a good idea to remove the gate valve handle so no one can adjust it again, you might also label each valve so you know which one to close in an emergency.
Good luck Martin

 

[mpullar]

Many thanks for your help guys, very much appreciated