Best practice in location of isolation valves

[puzzlebobble]

I'm going to be draining down my system this weekend. It's an open vented fully pumped system with a conventional boiler and two mechanical valves.

The only place that there are isolation valves is either side of the pump. Is it good practice to have them elsewhere in the system? I have the perfect opportunity to fit them when I drain it down.

Are there any other suggestions of things I could do to improve the system while I have the opportunity? (I'm going to pop in a magnaclean already)

Thanks for any advice on this!

 

[cowley]

You don't really need anymore valves, if you have balafix type pump valves you could change them for gate type for future pump changes as the balafix type tend to leak when turned off or on.
Don't fit any type of valve in the open vent or cold feed pipes.
Make sure you have drawoff cocks at low points in system and air vents at high points, flush out system well and refill slowly venting from lowest points upwards to remove air.

 

[puzzlebobble]

Thanks for the helpful advice Cowley.

You mention not putting any valves on the cold feed pipe. I'm draining down the system because I think the cold feed is partly blocked (vent spluttering and a horizontal section likes magnets: as discussed on; //www.diynot.com/forums/viewtopic.php?t=128927 ).

I was wondering about putting an isolation valve in where I remove the blocked segment of pipe because it would be easier to cure if the blockage happened again and there are two other approx. horizontal segments on the way up to the tank which I guess would have the potential to block. I won't now you've said it's a bad idea but it'd be nice to know why. (the vent is a separate 22mm pipe).

Ta

 

[cowley]

The cold feed is also the expansion pipe and should never have any sort of valve fitted to it mainly because a valve could be turned off and forgot leaving nowhere for the water to expand apart from open vent that is.

 

[JohnD]

If any of your radiators are fed from drop loops coming down from the ceiling (this usually happens if you have a concrete floor) then you need a radiator valve with drain-off on each such radiator.

It is useful to put in a full-bore drain cock as the fast drain helps wash out sediment. Many drain cocks are quite slow.

If you are planning a drain-off, lay in a stock of new washers for your drain cocks before you start. You will probably have to go to a plumbers merchant.

 

[puzzlebobble]

@Cowley

Ah, thought it might be something like that. Ta

@JohnD

Thanks for the ideas. I have only got a radiator valve type drain cock so a full bore one sounds like a useful and easy thing to add. I'll get spare washers too.