Bit of 42 copper + 2 x 42-22 reducers. Job done.
OK, so where do I get 42mm copper and 42-22 reducers? Best I've found is 35mm at plumbase (and I have to buy 3m!).
Update: I've found some 42mm 1.5m, at jtm plumbing online but I think I now have a better solution.
CH Sytem vent pipe diameter
- Thread starter vexation
- Start date
OK, so where do I get 42mm copper and 42-22 reducers? Best I've found is 35mm at plumbase (and I have to buy 3m!).
Update: I've found some 42mm 1.5m, at jtm plumbing online but I think I now have a better solution.
Sponsored Links
If you have a problem then its likely there is a better and easier solution.
Pumping over usually results from incorrect pipework connections and blockages.
Correct operation relies on a low resistance in the flow ipe between the vent and feed pipe. Rule of thumb says maximum of 150 mm spacing on a straight pipe.
But the 150 mm is a maximum and less is better!
Better still is the variation on a combined feed and vent as shown on the recent diagram.
Tony
Pumping over usually results from incorrect pipework connections and blockages.
Correct operation relies on a low resistance in the flow ipe between the vent and feed pipe. Rule of thumb says maximum of 150 mm spacing on a straight pipe.
But the 150 mm is a maximum and less is better!
Better still is the variation on a combined feed and vent as shown on the recent diagram.
Tony
I don't have a pumping over problem because the issue is surging at pump switch off. Cold feed and vent are about 2in apart. I'm pretty sure I have the right of it with it being ringing in the vent/feed U caused by the sudden stop shockwave.
This all depends on how much effort/money you want to throw at the problem.
The ideal solution would be to seal the system completely, what boiler do you have?
The ideal solution would be to seal the system completely, what boiler do you have?
Sponsored Links
It's oil fired, a HRM wallstar. Actually now I think I know what is going on I have a couple of solutions and I'll probably fit both. One is a check valve around the pump. I have one in system, but it comes from the vent pipe to pump output. I think it wants to be near the pump as once I have the shockwave in the vent pipe it a bit late. And two is a second cold feed connection to the vent so there is a loop for the oscillations to go around.
There shouldn't be any non-return valves anywhere, don't do that.
Try turning the pump speed down and possibly piping it like the diagram I posted.
Try turning the pump speed down and possibly piping it like the diagram I posted.
Non return valves are quite useful. When I had a coal fired back boiler I had one inline with the pump. The pump opened it when it operated and when the pump stopped it was closed by its spring. It prevent gravity circulation in the pumped side.
In this fully pumped oil fired system the non-return valve is around the pump as a bypass. It's in the same direction as the pump so if the pump is operating it would be closing the valve. It opens when the pump stops driven by the water surge to let that through.
The pump speed is already at 2 which is the right speed for a 10C drop across the boiler.
I know the benefits of non-return valves but they shouldn't be needed anywhere on a fully pumped system.
Being 28mm pipework you will have a very good flow rate and probably get away with pump speed on 1.
How many radiators do you have? What's the heat input of the boiler? (sorry if this has already been covered, there is a lot to read!)
Being 28mm pipework you will have a very good flow rate and probably get away with pump speed on 1.
How many radiators do you have? What's the heat input of the boiler? (sorry if this has already been covered, there is a lot to read!)
Perhaps I should have said I've measured the temperature drop across the boiler and adjusted the pump speed. Hence the 2 setting the pump is on is right.
But FYI boiler is 15kW, there are 16 rads, total ~13.5kW and house loss at -1C works out as 7kW (system has evolved somewhat). Pipework is a long run of 28mm with some 22mm each end before you get to the rads.
But FYI boiler is 15kW, there are 16 rads, total ~13.5kW and house loss at -1C works out as 7kW (system has evolved somewhat). Pipework is a long run of 28mm with some 22mm each end before you get to the rads.
You're thinking too much!
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
