Inhibitor for 50 rads

[emergencyman]

I've just done a drain down to repair a rad valve in a big building. There are 50 hospital radiators on 3 floors and recently added underfloor heating on the ground floor. Its a one pipe system in steel with most of the pipework in 2". I filled it back up on Friday and the tank was filling for 3 hours. I am going back Monday to check all is well and finish off bleeding the radiators. Any ides how much inhibitor to add? Thanks

 

[Roger Welton]

More than 1l thats for sure! Both fernox and sentinel say bottle for each 100l of system volume if that helps.

 

[GasmanxxxR1]

i reckon 7 bottles

 

[Roger Welton]

Cast iron rads and 2" pipe will kill the system volume though. I'd have looked at the water meter whilst refilling personally.

 

[emergencyman]

That's a really good idea Roger, I wish Id have thought of that on Friday, but its a bit late now. Assuming the ballvalve was filling like a tap on low for 3 hours call it 5L/Min that's 900 litres, that's 9 bottles, so Gassmanxx wasn't far off with 7. Do my sums sound about right?

 

[Leo21]

You'll need more than seven, a bottle normally does eight to ten rads. So on a normal system yes. But school rads and two inch pipe, no. I'd be at thirteen or there abouts.

 

[Ray Stafford]

Or invest in a sentinel test kit.

Chuck in about 7 or 8 bottles, leave it a while and go back and test it. Add more if necessary.

 

[Roger Welton]

Is it much cheaper to buy a 10l drum ray?

 

[Ray Stafford]

Is it much cheaper to buy a 10l drum ray?

Not that I can find. If you want to save money on inhibitor, go unbranded.

 

[emergencyman]

Thanks all. Just one more question, will the Sentinell test kit work on the unbranded stuff? I assume its all the same, so I am tempted to use the £5 a litre stuff.