I want to modify the pipework feeding a radiator on a combi boiler system but I could do with some advice on how to go about it as I am a novice at CH systems.
My idea was to use a couple of freezer kits that go around the pipe isolating the section, avoiding draining down the whole system. I havn't used these kits before, but guess that it is best to release the pressure in the system before starting. If I shut the water off at the house stopcock and open a radiator vent valve, will this be suffiencient to release the pressure in the system? I'm thinking about air stored somewhere - in a closed header tank?
When the pipework changes are done, are there any potential problems about getting any lost corrosion protection fluid / antifreeze back in - and getting any air out of the system to restore normal operation?
I have a thread somewhere up there ..around the 9th of Nov...for a similar situation 'cept I'm replacing a rad . I've done everything except connect up the new pipes ( the rad is a different size) and what I am going to do is shut off the boiler ( Combi sealed system) ,close off all the others rads incl using decorators caps,drain down the pipework ,cut the pipes to the old rad and join the new piping then close the drain tap,fill up using the filling loop having added some additional Sentinel and bleed the system .
Why? If it's difficult to drain at the moment because of a poorly positioned drain now's the time to sort that.
It sounds like you're not terribly experienced and those freezer thingies cost a lot and of course soon melt. Just what you need half way through the job. And it would be a good time to add new inhibitor as well.
If it's a sealed system their should be no water feed to it anyway. The filling loop should be disconnected after use. If an open one with header tank there should be a stopcock - or you could tie up the ball valve.
Pressurized systems don't normally airlock so are just bled in the usual way. Best to do all this and make sure there are no leaks on the new work before partial draining down again to add inhibitor. The normal way is to use concentrate and a gun - same as the ones for sealers - and the concentrate should come with an adaptor tube to feed in via a bleed screw.
I've seen this mentioned a few places but never seen an explanation as to why it need be removed . It was connected on my Alpha when it came out of the box and has styed in situ ever since .The fitter made no mention of removing it ....not sure what the manual says ( must look) but surely if the taps in the loop are in the off position thats good enough . Seems more convenient to have it connected rather than faffing about anytime u need to topup ..even if it is a rare occasion. Anyone know?
If a tap is left on a little, the system could continue to fill without being noticed. If you get the habit of disconnecting the fill loop after topping up, you notice quicker that a tap has been left on, at either end of the fill loop.
Literally, yes. :-) But with those little flappy paddle taps, it is possible to leave one on a little. The same happened to me with a washing machine valve. Just didn't tighten the tap off as much as I should have. The tiny drip, and it was tiny, over a week of being left unattended, didn't do the wooden floor much good. :-((
No it wouldn't ....I have a wooden floor immediately below my boiler so if I took the loop off and there was drip from the tap my floor would get it .However the boiler is right next to the sink so a glance across daily can tell me if the pressure is going past where it should be ....altho' it won't be cos the taps are def OFF :-)
I think it is also to comply with regulations - you wouldn't want your C/H water back feeding into the water mains if the mains pressure fell.
Incidentally - back to the pint - Will the system the OP has have an accumulator - air pressure thing. If so some water will still be under pressure when it is isolated.
Probably.. there is the little thing about expansion and a filler loop is stopped at both ends so if the temp changes it may become stressed depending on what its made from.
On Tue, 18 Nov 2008 16:31:03 -0000 someone who may be "Roger R" wrote this:-
I would advise not using these kits by novices, who tend to work slowly and may come to a sudden stop when they discover the bit they have forgotten. It is not good to then be worrying about the ice plugs melting.
I suggest draining down the whole system, as had been said this is the time to fit drain points to make future work easier. If necessary you can then put in a system cleanser (if you don't know the history of the system), then inhibitor. These can be put into radiators with a suitable gadget, there should be instructions with the bottle it comes in. To take one example,
comes with a little pipe which fits into a radiator.
You shouldn't need to turn off the main house stopcock, as the radiator water is not permanently fed from the mains supply.
You boiler probably has an expansion vessel inside it, so if you can isolate the central heating pipes at the boiler, then do it. - make sure your boiler is off during this work!)
Now, where is it you will be cutting the pipe? Assuming you are! If it is under a floor, I would just use a pipe slice and cut the pipe, then shove a push fit (reusable) end stop on the end - water loss should be minimal (last time I did it, it was probably less than 1/4 litre)
If you plan to solder the pipe, then this won't work, as it needs to be dry - if you are going to use push fit fittings, then this should be really easy!
If you don't fancy doing it like this, then you need to drain the pipe work (not the whole system)
To do this, you need to go round and turn off all the radiators you don't want to drain (Including turning off the lockshield valves, but make sure you make a note of how many turns that are set to now, so you can out them back as they were.
Now isolate the CH pipes at the boiler if you can.
Now open your drain valve(s)
When the water stops (or almost stops) go and undo the bleed screw on and radiators you need to drain (You may not need to drain any, in which case, undo the nut on the pipe entering the radiator you are working on (on the pipe side) a little (you should hear air being sucked in)
If you are altering the other pipe on this radiator, do the same to this.
now your pipe work should be mostly drained, so you can disconnect the pipe fully.
If you blow down the pipe hard, this will expel any remaining water!
Complete you alterations and reconnect the radiator
Now to refill...
Close the drain taps!
make sure all your connection are tight
if you drained the radiator, close both valves now
If you isolated the boiler, go and open one of the valves.
Go to your radiator and open the bleed screw
open the lockshield valve, and observe if it hisses at you If it doesn't, close the lockshield, and open the other valve
If it still doesn't, then the boiler has lost pressure, and needs to be re-pressured - open the other valve on the boiler, and then partially pressure the boiler using the filling loop (So, say 0.5 bar)
now go back to your radiator and open the lockshield - it should hiss this time! Close the lockshield and do the same with the other valve, then close it again
Check for leaks in you new pipes
If it stops hissing, before water emerges from the bleed valve, close the lockshield again, and go and re-pressure the boiler using the filling loop
Again, keep checking for leaks in you new pipes!
repeat until water squirts from the bleed screw.
Now bring the pressure up to 1.5 bar (Or whatever is normal on your system), and check for leaks in the pipe work you have altered
Check the pressure again, and refill if required
If you can run the pump up on the boiler, without firing, then do this for 5 minutes or so, turn the boiler off again, then bleed the radiator you are working on (leave all the others off for now) If not just turn on the boiler, but keep the thermostat on the boiler low.
Go round and reset all the radiator valves back to their original positions.
check the pressure and top up if required
Run the boiler again for 10 minutes (pump only if you can, or just on low)
Go round and bleed all the radiators (there shouldn't be much air in them, but there may be a bit!)
Oh Yeah....Regulations....regulations...regulations. You always keep to rules do you :-) This damn Country is overrun with regulations and this is one that I am going to continue to ignore .
Trouble is you might contaminate other's drinking water too - not just yours. Unlikely I know. Of course if you want to drink water that's been lying around in your boiler etc for ages and mixed with gawd knows what that's your business.
When I turn the FL taps off I turn them OFF .I'm the only one in this flat so unless the taps find some way of turning themselves on then there won't be a problem . I appreciate tho' that not everyone is in this position and there might be little hands fiddling with the taps .:-)
On Wed, 19 Nov 2008 12:45:53 +0000 someone who may be snipped-for-privacy@gmail.com wrote this:-
If your water system is entirely separate from everyone else's, if you have a borehole or collect water from the roof for example. However, that is unlikely in a flat and as soon as your water system is connected to that of others then it is possible to contaminate their supply.
There regulations were not introduced on a whim, there were cases of this sort of contamination. One may argue that the risk is low, but it is not so low that the risk should be ignored.
I'll take the advice, avoiding the freezer kit and drain down the rad.
I now understand about the filling loop and how it is used, that it is unnecessary to shut off the water main stop c*ck while doing the job, which will enable refreshments to be available at intervals.
Incidently the boiler is in the garage and the rad is upstairs in the bathroom, so that proabably makes it a bit simpler.
Inhibitor in tubes. I noticed them in the DIY shed today.
You strike a chord there as I often find the necessity to visit the diy shed in the middle of a job.
The boiler is in the garage and the rad to be worked on is in the upstairs bathroom. I will probably be able to just drain that one down without needing to drain the whole system as it is quite recent, no more than two years old.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.