Removal of taps when no isolation valve

28 Feb 2008
Reaction score
United Kingdom
I need to remove the hot and cold taps in my downstairs kitchen but there are no isolation valves in the pipework under the sink. The HW + CH system is run on a Potterton condensing combi boiler. The mains water stopcock is under the sink and functional. How can I remove the tap tails and replace the taps without flooding the house? Any advice appreciated.
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1. Turn the main stop cock off, and turn the boiler off.
2. Turn on the taps you want to replace. You should get a little residual water from the pipes, then nothing. If this works OK you have isolated hot and cold. If not, you have stored water and its more complicated.
3. Undo the tap tails. Again you will get a little residual water, so old towels, buckets, oven pans to the ready.
4. Remove and replace the taps.
5. If you feel like it, install isolation valves. Go for full bore ones of a reputable make, like Pegler.
6. Attach the new tails to the pipework. If you have installed isolation valves, don't connect the flexi's directly to the valves but use adaptors.
7. Some tap tails (e.g. Grohe taps) end in 3/8" BSP female connectors. These need different adaptors to go onto the valves.
8. For adaptors look at Screwfix 2665R for normal 1/2" and 6089R for 3/8" ones.
Hi oldbuffer
Many thanks for your detailed response. That's brilliant. I don't have any tanks or stored water to my knowledge so I expect the residual water in the pipes will be all I get. I'll follow your instructions to the letter. I will also fit full bore isolation valves as suggested. Thanks again. Much appreciated.
Close main stopcock .And turn off boiler. Turn on all hot and cold taps upstairs and downstairs ,to drain all water from above .
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And watch out when you turn them back on - they don’t half spurt when the air is coming out!
Hi All,
Well taps removed and two Isolation valves now fitted. No problems. Thanks again. My next job is to replace a radiator in my dining room. The Rad is fitted with a lockshield and a Thermostatic Valve and is plumbed in with 10mm Hep2O plastic piping. Is it a similar procedure as for the taps.. ie. Stop Cock closed, combi boiler off, and then do I need to drain the heating system pipes as well as the radiator. Do I drain the system from a drain cock somewhere? Help again much appreciated
Is it a like for like swap ,retaining the original valves in their existing positions ?
Or do you need to fit new valves / ammend the Pipework ?
If it is the latter ,electrically isolate the boiler ,drain the system .
Hi terryplumb
OK thanks. It is a like for like replacement, no change of valves etc. To drain the system do I look for the lowest rad with a drain off valve and attach a hosepipe to the grid outside, open the valve and wait until the water stops flowing? The lockshield on the radiator has what looks like a drain valve with a square headed valve head that sits inside the drain point, so you wouldn't be able to open the valve when the hosepipe is pushed over the drain point !!!!!!! Not sure what this is for.
Show us a pic .
If you don't intend to move any valves or pipework ,then you don't need to drain the system . Just drain each rad ,manually . Or possibly via the drain cock on each rad ,but need to see pics of what you have.
If you don’t have to remove the valves from the pipes, there should be no need to drain system. Just turn the valves off disconnect them from the rad, remove rad, replace rad (you may need to reuse the rad tails from the original rad if new ones are different), open valves and bleed just that radiator. You will need to top up the system pressure as well.
Sorry, I intend to move the radiator to a different location in the same room. I am having the wall removed that the radiator is fitted to, and an RSJ fitted. I really would like to stop end the existing pipes until I am ready to re-route the pipes through the ceiling void down to the new location. I will take a photo of the current lockshield with the square valve and post it tommorrow.
That's not a like for like replacement Joe. You will need to drain down to do that.
I meant I will be using the same radiator and valves when it is ultimately relocated. OK, drain down it is. I'll look for a drain down point on the ground floor.
No drain down needed. If it’s a combi and you just want to stop end them for now, turn off both valves, remove rad, open one valve to let the pressure out of the system (about a gallon or so) then quickly remove the valves and fit stop ends. You’ll only get a trickle of water from them as it’s a sealed system. Don’t forget to repressurise the system afterwards.

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