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.

 

[Leo21]

Let us know how many it needed. We,ll be taking bets.

 

[Ray Stafford]

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.

No, its not necessarily the same. Each manufacturer's test kit is only guaranteed to work with their formulation. Thats not to say it won't work, just that you can't be sure.