Combi boiler - removing and capping radiators?

[disco_monkey79]

Hi

Any plumbers on here? I recently moved in to a new place with a combi boiler.

I'm decorating, which will entail removing radiators in order to decorate behind them.

Someone has suggested that I can remove one or 2 rads, and temporarily cap off the pipes, which will enable me to re-pressurise the system and continue to use the boiler (which would be good as it's the source of the hot water for washing etc), and heat the rest of the house.

Is this correct? Can the system still work with one (or more ) radiators capped off? Surely that stops water from flowing throughout the system? Or does the water flow from the boiler to each rad separately, rather than on one big loop?

Beyond changing tap washers, plumbing is entirely new territory, so apologies if this is an ***** question.

 

[That would work]

Yes the rads tee off a circuit so shutting off or capping the flow and return to a rad wont affect anything providing its been plumbed in correctly. I am not a plumber btw but ive done a lot of this stuff.

 

[Phil Pascoe]

If you or the trv shuts the radiator off in effect you are isolating it from the rest of the system. It is fed off the loop, the loop does not go through it - if it did you would shut the whole system down every time one radiator turned off. Each radiator has a valve at both ends - just turn both of them off, put something under it to catch the water and often you can loosen the nuts, drop the radiator forward without taking it off completely, paint behind it then re hang it and do the nuts up again. Ensure afterwards that there are no leaks. You need to bleed the radiator and top the system up to replace the lost water - it's a good time to get some Fernox or something in it - if you reconnect the rad, before filling it up again take one of the top bungs out and make up a small funnel and pipe to pour the stuff in from the top.

 

[Sheffield Tony]

There's one possible gotcha - it is necessary to make sure there is some flow, even when all the TRV's close, so that the pump doesn't get stalled. Possible ways of doing it include leaving one or more radiators without a TRV, but with manual valves that will never be fully closed. Often the bathroom radiator. Or the one in the room with the (electrical) thermostat. So if you have to remove that radiator, it might be best to be sure there is another bypass route - if necessary removing the head of a TRV elsewhere while you do the job. Newer systems tend to use a pressure relief bypass valve.

I have has some luck, depending on rad design, with removing one of the plugs from the top (the one with the bleed screw) and siphoning out the water with a bit of plastic tube. Makes less mess on the floor. I did see once tails that had two shut-off valves, so you could isolate the rad from the system, then remove the radiator with water in situ. Sounds like a neat idea until you come to try to lift it :lol:

 

[Bm101]

Might be worth getting the system flushed and fitting a magna clea? Again, not a plumber but a relatively simple job (for time and equipment) and you're running a clean system that should make a difference to your boiler lifespan. Be interested to see people's views on the efficiency of doing it.

 

[disco_monkey79]

Thanks all. I don't want to pull them all off at once - I can just do them one at a time.

I like the idea of loosening and tilting forwards, but it's nice to know I can remove them entirely should it be required.

Thanks again.

 

[sunnybob]

If you have TRV's, at LEAST one radiator MUST have manual shut off and not all TRV's. You risk blowing the boiler otherwise.

You can buy plastic caps that replace the TRV heads which shut the valve fully. You have to be careful if you only rely on a TRV to shut off the rad, If the room temp changes the valve may open and flood the place.

But as said above, the simplest way is to loosen each rad as you come to it (with the boiler OFF) and paint paste behind it and re install before moving on to the next one.
If youre really lucky, the rads may be fitted with micro bore copper pipe (10, 8, or even 6 mm). This is soft copper, and depending how much free pipe you have it may be possible to gently move the rad without touching any fittings at all.

 

[Marineboy]

If you have TRV's, at LEAST one radiator MUST have manual shut off and not all TRV's. You risk blowing the boiler otherwise.

You can buy plastic caps that replace the TRV heads which shut the valve fully. You have to be careful if you only rely on a TRV to shut off the rad, If the room temp changes the valve may open and flood the place.

But as said above, the simplest way is to loosen each rad as you come to it (with the boiler OFF) and paint paste behind it and re install before moving on to the next one.
If youre really lucky, the rads may be fitted with micro bore copper pipe (10, 8, or even 6 mm). This is soft copper, and depending how much free pipe you have it may be possible to gently move the rad without touching any fittings at all.

All combis have a pressure relief valve so won’t blow up even if all rads are locked off. But it is good practice to have one rad without a TRV, as previously said either on the bathroom or room where the stat is.

 

[whiskywill]

If you have TRV's, at LEAST one radiator MUST have manual shut off and not all TRV's. You risk blowing the boiler otherwise.

Not true, Sunnybob. You are overreacting, as usual. :roll: Don't most, if not all, boilers have a built in thermostat which will protect it if all of the thermostatic valves are closed.

 

[sunnybob]

and you are prepared to guarantee that the old valve on the old boiler is fully operational? :roll:
I made a good living cleaning and replacing blocked safety valves on pressure vessels, some of them would not have blown at 5 times the rated pressure.

I dont over react, I make very sure that safety items are in full operational order.

 

[HappyHacker]

Good advice above. Watch out if you use a TRV to shut the radiator, some have a locked off position some do not and cannot always take the pressure and leak. DAMHIKT. Mine was OK until the system heated up and the pressure increased.

Not all boilers require a bypass and if they do this is normally provided by a towel rail or a rad without a TRV. It can also be a separate bit of pipework somewhere. It is bad practice to use all TRVs on a boiler that needs a bypass.

 

[stuartpaul]

Might be worth getting the system flushed and fitting a magna clea? Again, not a plumber but a relatively simple job (for time and equipment) and you're running a clean system that should make a difference to your boiler lifespan. Be interested to see people's views on the efficiency of doing it.

Chris, - we’ve had magna cleans on our last two systems and they certainly do a good job of collecting crap in the system. The people who do the servicing make a simple point, - the crap on the probe is crap not circulating through your boiler/heating system so it’s more effective.

Does it prolong system life? No idea but for the minimal additional cost of fitting one it can’t do any harm.

(I didn’t write rubbish! Some swear filter)

 

[Lons]

Just one point not sure if it'e been mentioned but important.

If you empty any of the rads you MUST keep a careful eye on the combi boiler water pressure and if /when it drops you have to fill to the indicated pointer using the filler loop.

If it is microbore be very careful as bending can easily kink the pipe, not something to be recommended.