Adding a rad without draining down

  • Thread starter sparkyspike
  • Start date
S

sparkyspike

Hello.

I need to fit a new radiator in the kitchen. I have a Baxi Combi HE which is big enough for the job. The flow and return from the boiler (also in the kitchen) is 22m going to a 4x 8mm manifold for each leg. I want to tee off on the 22m legs for the new circuit (only 4m long).

My plan is to leave all bleed valves closed and to open the drain cock to drain the pipework below the boiler. I would imagine that most of the water will remain in the pipes. Then I can use a compression tee on each leg. Once the new radiator is connected, I intend to use the filling loop to fill the new rad until the pressure is back up. Then use the bleed valves to get rid of the air.

I am hoping that I won't have to add any more Sentinel as it was only done about 4 months ago when the boiler was replaced.

So my question is, is there a flaw in my plans? Will I really be able to hold the water in the system whilst I fit a pair of tees? And will I have to top up the inhibitor and if so, can I do this first by pouring some into the new rad by removing the bleed valve?

I hope this makes sense and what I'm trying to do isn't really stupid...
 
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It's a disaster waiting to happen.

Drain down and do the job properly!
 
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sparkyspike

Any particular reason why it's a disaster waiting to happen? :?:
 
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You sound like you have the correct idea, its a sealed system so not that much water will come out after you have cut the pipe, just have lots of olds towels near by and a couple of buckets.

no harm in squirting in a new bottle of inhibitor to the system, before you fill back up, maybe only use half a bottle.

Good luck!
 
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Any particular reason why it's a disaster waiting to happen? :?:

Yes, the water! If you can positively ensure that the water is stopped then you'll be ok. I've saved inhibitor before by closing all the rad valves, taking a note of the lockshield settings, but still draining down the pipework. In my experience unless this is done, you can get a gurgle then a flood at very short notice.
 
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what is the problem with draining the system?
it is a sealed system so chances of airlock problems are next to nothing
 
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what is the problem with draining the system?
it is a sealed system so chances of airlock problems are next to nothing
 
S

sparkyspike

In light of all your replies, I'll close all the rad valves and isolate the boiler and drain down what comes out. I can't imagine I'd lose so much water in an 8mm system anyhow. Plus I haven't fitted the kitchen yet, so a small flood would be bearable. I guess I'll go and buy a bottle of inhibitor in the morning and give it a bash!

Thanks for your replies.

SparkySpike
 
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If the isolation valves to the boiler are quite old they sometimes have the habit of leaking (especially the slot head screw driver ones). So, IMHO, if you can avoid turning them off and on. do so.
 
S

sparkyspike

Ok. I've done the job and all is well. I'm afraid I used solder ring fittings though :oops:.

I was just wondering - I lost about half a bucket of water when I drained the pipework. Would I still need to add any more inhibitor? It was put in a few months ago when the new boiler was fitted.

SS
 
S

swidders

Ok. I've done the job and all is well. I'm afraid I used solder ring fittings though :oops:.

Nothing wrong with these - some of my lazier colleagues love these with a passion.
Well done on getting it done.
I was just wondering - I lost about half a bucket of water when I drained the pipework. Would I still need to add any more inhibitor? It was put in a few months ago when the new boiler was fitted.

SS

So, you spent a thousand or so on a new boiler etc, but don't want to spend an extra tenner trying to keep it free from potential corrosion? I see
 
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No it's not that - I just wanted to know:
I lost about half a bucket of water when I drained the pipework. Would I still need to add any more inhibitor?

?

It would be prudent to add another bottle of inhibitor in my opinion. You can buy test kits but it may well cost as much as a second bottle. If you don't know the volume of the system, you can't be sure how much inhibitor is still in there without a test kit.
 
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cost of good inhibitor: 15 quid
cost of cleaning system caused by lack of inhibitor: day's labour to clean plus repair of damage, your guess is as good as mine.

is that coffee i am smelling?
 

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