How much inhibitor

[Fredstudio]

I need to add inhibitor to a system after a drain down. There is 13 rads. On the system and a small section of underfloor heating serving one room and a hall way. How much sentialx100 would I need. Thank you

 

[Mottie]

I'd say two litres.

 

[Fredstudio]

Thanks some are doubles. And 4 column radiators

 

[Mottie]

I have 10 rads, some doubles, and I have one litre in the system which is why I suggested two for your system. You could always try it with one litre and once it had been in the system for a while and thoroughly mixed in, test it. I draw off half a cupful. Into that I drop a steel nail. Into another half cup of tap water, I drop another steel nail. Compare them after a few days to see if your inhibitor is doing its job. If not, add another litre. This is how mine turned out - you can see which side has the inhibitor and which side is just tap water.

 

[Fallout]

So one litre was enough on yours

 

[Wayners]

You can buy water test kit to see if it's strong enough mix but I don't think you can add too much so put plenty in.
That's what I did.

I put another bottle in last year after I took two rads off for painting..

 

[fixitflav]

You can buy water test kit

Cheaper to do Mottie's test. I do that once a year on my system.

 

[Wayners]

Yeah. Clever.

 

[fixitflav]

Yeah. Clever.

Thanks

 

[Fallout]

How do you work out how much is needed if underfloor heating?

 

[Wayners]

How do you work out how much is needed if underfloor heating?

Length of pipe at so much water per metre or mottie test or buy kit off eBay and test concrete.

I'd just Wang loads in. My system has had 3+ bottles in over last 15 years