Finding CH draincock

[phil090207]

I've bought a new house and I'm upgrading the open vented CH system. I'm adding a mid-position valve so the existing CH gas boiler can supply the existing indirect hot water cylinder too - the cylinder is currently heated by an AGA cooker which I'm removing.

But I can't find a drain cock anywhere obvious. The DIY guides say "the drain cock will be found in the return pipe near the boiler". Not on this system!

The boiler and HW cylinder are both upstairs - the 28mm feed/return pipes from the boiler split into two pairs of 22mm pipes, one pair serving the upstairs rads and one pair the downstairs rads. To do my job, I don't need to drain the downstairs rads (in fact would prefer not to), so any drain point below the boiler would be fine.

So before I start taking the whole house apart looking for the mythical drain cock, are there any places I should look first - where do plumbers tend to put them? Before the other trades cover them up again

If I fail to find a drain cock, can I use a clamp-on screw-in valve - the kind used to install a washing machine to an existing pipe - to create one? Or would I just create a flood? I wonder if these are available in 22mm size, I've only seen 15mm. Once drained I could fit a proper draincock to replace the clamp-on valve. If so where on the system should I put this?

Thanks for some advice.

Phil.

 

[RigidRaider]

Some advice, if I may, as we've just done all this:

1 - You'll get a good price for the AGA on Ebay. That's where we bought ours. Otherwise Google or check Ebay for firms who specialise in removing and reassembling AGAs because there's a thriving trade in second hand reconditioned ones.

2 - You could keep the AGA and just remove the boiler from it, which is an inefficient way of heating the water and which will leak eventually. The firms mentioned above will do that and service the AGA for a competitive price.

3 - It's quite possible your CH system desn't have a drain cock. If so, think carefully about where you might install one. Then do the job properly with a spur and a decent cock. Don't go and buy one of those cheap little brass 15mm cocks, they leak as the washer inside collapses. We had a flood thanks to one of these.

4 - When installing the drain cock you might not need to drain the system down, if you fit a stopcock in the downward supply pipe from the header tank and temporarily fit one on the expansion pipe. By letting some water out of a radiator you might be able to get the water in the system to "hang" while you install the drain, quickly.

 

[phil090207]

Thanks RigidRaider.

Funnily enough our AGA is listed on ebay right now at what I think is a good price, 12 people watching but nobody asked to come and see it yet (surely a serious buyer would want to see it first?). Still 5 days to go.

If we can't get a good price for the AGA I had considered keeping it and switching off in the summer. My idea was to add valves such that I could switch to either the AGA gravity-fed circuit (winter) or the pumped gas boiler circuit (via the mid-pos valve, AGA off) for summer use. I haven't figured out where these valves would go but it sounds possible? But perhaps your suggestion of decommissioning the AGA boiler entirely and using the gas boiler for HW year-round is better. I dont' know which is more efficient, but the boiler is certainly more controllable - I can boost the HW when I have guests, etc. Also the AGA HW is ridiculously hot, and AGA tell me there is no way to thermostatically control it. They suggest a hot-cold mixer on the tank outlet - how daft is that?! I've just installed a cylinder stat in readiness for the mid-pos valve so I'd like to use it and save some gas.

Back to my draincock question - perhaps I can drain the system enough just using the downstairs rad bleed valves. We have victorian cast-iron rads with chunky bleed valves, they even have little nipples to which a hose could be attached. Since my job is upstairs, this might do the trick?

Phil.

 

[RigidRaider]

You probably know TN Cook in Skipton? Ben Cook told me that the AGA is a terribly inefficient way to heat your water; you're best off removing the AGA boiler and using the house gas boiler. However in our previous house we had an AGA that was supplementing the gas boiler, to what extent I have no idea, but in summer when the AGA was off the boiler used to just take up the slack. There weren't any valves to control it, I think the AGA gravity circuit was feeding a second coil inside the cylinder.

I would think it a shame to remove the AGA but then we are AGA fans, big style. Is that your red one in Keighley? So you do know Cooks! Coincidentally we got our green 2 oven from Keighley!

On your rads, yes, as long as you can find a way of getting the water level down below the place of work without flooding the house, anything goes! A permanent drain cock is useful though, it makes repairs or alterations so much easier. I plan to fit one in the garage, because the floor is below the level of the ground floor heating pipes so I ought to be able to drain the system almost dry.

 

[phil090207]

Thanks for the advice - yes that's our red AGA on ebay, we're in Kildwick which is half-way between Skipton and Keighley. We'll see if it sells on ebay, if not, we might keep it but get the boiler shut down.

Now I just need a teeny hose pipe connector to fit the nipple on my radiators...

Phil.

 

[phil090207]

I've now completed this job - I didn't find a draincock, but I did find a self-cutting draincock fitting (15mm) in B&Q, which I clamped to one of the downstairs rad pipes - above floor level so I can see if it ever leaks! This doesn't quite drain the bottom of the system but is fine for working upstairs.

I've used self-cutting taps several times to install washing machines etc, including on mains-pressure pipes, and always found them to work perfectly, so I can recommend this method.

Phil.