Topping up Central heating inhibitor

[theone8181]

Hi sorry for the odd topic, but we have a vented, mavity fed central heating system. I recently had a leak that involved a lot of water coming out the system. The guy that fixed it recommended topping up the inhibitor, but I'm not sure which tank to put it in. I've got a big tank a small tank and there may be a 3rd tank under the big tank (hard to tell as access is difficult in the loft). Sorry to sound stupid, but I just want to be clear on it being the right one. I was thinking of asking the guy that fixed it as he's my neighbour, but I feel bad as I pounced on him as he got in from work.

 

[drakulton]

The small tank is probably the central heating header tank and the big one the header for the hot water.

 

[theone8181]

Cheers, the small one does look more furry, guess it doesn't often get emptied.

 

[drakulton]

Yeah, if your heating system isn't leaking, then it's not likely to constantly topping itself up.

 

[FlyingFish]

It's the small tank that feeds the heating circuit, so that's where the inhibitor goes. But your best to get the chemical in the system directly, rather than have it sit in the tank. As the system uses water from the tank at a very slow rate, and expansion /contraction isn't going to get it in that quick either.

Better to drain some water out of the system (without the tank filling, turn the cold mains off) then add the the inhibitor in the tank, then fill the system back up.
Or get the aerosol type that directly injects into a radiator.
Or drain a radiator, and put some inhibitor on the top.

 

[theone8181]

It's the small tank that feeds the heating circuit, so that's where the inhibitor goes. But your best to get the chemical in the system directly, rather than have it sit in the tank. As the system uses water from the tank at a very slow rate, and expansion /contraction isn't going to get it in that quick either.

Better to drain some water out of the system (without the tank filling, turn the cold mains off) then add the the inhibitor in the tank, then fill the system back up.
Or get the aerosol type that directly injects into a radiator.
Or drain a radiator, and put some inhibitor on the top.

I was thinking of option 1, but I'm concerned cracking the valve will end badly.

 

[ANDARIAL]

Or drain a radiator, and put some inhibitor on the top.

This is a better idea imho

 

[theone8181]

This is a better idea imho

Am I right in thinking there's a special kit for it?

 

[ANDARIAL]

Yeah but you can make one.a funnel and a piece of pipe and carefully pour would do

 

[theone8181]

Yeah but you can make one.a funnel and a piece of pipe and carefully pour would do

How do you overcome the pressure?

 

[ANDARIAL]

Turn off both valves to rad.open bleed point.drain a little bit of water and fill with inhibitor

 

[theone8181]

Turn off both valves to rad.open bleed point.drain a little bit of water and fill with inhibitor

I'm thinking of banging in a litre though, I'd be there for ages at the bleed valve .

 

[ANDARIAL]

Once the pressure has dropped you could take out the whole plug.
With a kit you can squeeze and force it in quicker.about a fiver i think

 

[theone8181]

OK might have a look.

 

[theone8181]

Just googled, I see what you mean now.