Inhibitor or Antifreeze for central heating system

[Kaymo]

Hi all,
I have just fitted a new radiator and magnetic filter to my central heating system and now that I am satisfied it is holding pressure with no leaks I am trying to figure out now whether I need to fill with antifreeze or inhibitor - (currently filled with water only).

Given that I have 20 radiators it looks like £20-30 for inhibitor against £100+ for antifreeze but dont want to scrimp if its needed. My boiler is a Bosch 42 CDi fitted just over a year ago by an approved installer and from a quick internet seach I think it has built in frost protection so I presume this means that if the temp at the boiler gets below about 4 deg the boiler will come on anyway so does this make the antifreeze reduntant?

Boiler is in the garage which is connected to the house, and many of the pipes run under suspended floor but are all either insulated with modern insulation or the old fashoined stuff wrapped around the pipes with wire.

Thanks in advance.

 

[Armo74]

Inhibitor, Would have been a good idea to add it when you swapped the rad though you could have poured it in before you fitted the vent.

 

[ianmcd]

you should definately add inhibitor, your boiler has a frost protection device but this is only designed to protect the boiler if you want antifreeze protection along with inhibitor then use Sentinell X500 it does both £39.99 from Screwfix, depending on the make of your magnetic filter it would probably be easiest to install it via that

 

[gas112]

Anti freeze usually asks for around a 25% concentration of the system so luckily enough yours doesnt require it as the built in protction and no pipes heading outside so just inhibitor will do it

 

[Kaymo]

Thanks all for your comments, I am aware that I need a corrosion inhibitor, my question was whether I need a corrosion inhibhitor 'with antifreeze'. By the sounds of the comments I dont, which is good as the system is quite big and 25% would have been a lot of expensive antifreeze! I am still a little concerned about the pipes that run under the suspended floor as this is fully vented to outside but maybe the money spent on antifreeze could be better spent on improving the insulation on the older sections of pipe.

P.S. The reason I didnt fit it while the rad was open was that I was also repairing a problematic leak on a very very old T-section that I wasnt convinced would seal so I thought it was better to fill with water only until I was confident that it was holding pressure.

 

[CBF]

& if your installer had done the job correctly he would have fitted frost & pipe stats in the garage

 

[Kaymo]

& if your installer had done the job correctly he would have fitted frost & pipe stats in the garage

Dont get me started on the installer, it was part of the quote to fit the magna filter as well but he didnt and when I called and left messages he didn't respond - hence the reason I bought and fitted it myself.

 

[gas112]

Boiler has a built in frost stat so installer didnt need to fit additional stats

 

[CBF]

Boiler has a built in frost stat so installer didnt need to fit additional stats

wrong the internal frost stat only protects the boiler, the OP already stated he has exposed pipework therefore what happens if the pipes are frozen due to wind chill or anything else before the boiler frost stat kicks in & the boiler starts jumping off the wall, you can't just rely on the frost stat built in he should have fitted a seperate frost & pipe stat

 

[Boilerman2]

Problem is boilers with built in frost protection are desgined only to protect the boiler from frost, I have seen numerous occasions when this internal frost protection has failed to stop a burst pipe next to the boiler so if a boiler is fitted in an attic or garage or other un-heated space, then an air and pipe frost stats should always be included

 

[leakydave]

And of course another consideration... your boiler only has frost protection when there is gas and power going to it.

In a power cut you would be stuffed! And pay your gas bill!

 

[Kaymo]

Ok, now I am even more confused

Would I be right in saying that there are differing opinions on whether antifreeze is required? I suspect the installer only used inhibitor last year but then last year was the mildest of the last 3 winters.

I suspect that with the fact that the boiler is protected by a frost stat, and the pipes are insulated it will need to get considerably below zero outside for the pipes to freeze but its still a concern given I recorded -18 outside a couple of years ago!

I suppose worst case scenario is probably a burst pipe in the garage, which will run into the drain or a burst pipe under the house which will drain into bare earth, then I repair the pipe. As an Engineer and former mechanic, basic plumbing is not a problem so I am not in the same scenario as a pensioner who could lose their heating while waiting on a plumber to arrive. I do have a wireless stat that i've just added that I could use in place of a frost stat if it get very cold.

I am curious as to what you guys do in your own or customers systems? Would you fit antifreeze in this scenario?

 

[Boilerman2]

When I install External oil boilers I always use Fernox Alphi 11 antifreeze/Inhibitor, bu depending on the level of protection you want as you say it can get expensive, also don't expect to be able to use a pipe freezer kit on a system treated with antifreeze, meaning that after draining new treatment would be required so it's swings and rounderbouts TBH, you pays your money and you takes your choice on internal boilers even in garages I would not normally use antifreeze but that is just my own opinion I am sure that many on here will say diffrent!!