Insulating pipes already insulated with old pipe felt

[nimh]

Hi

I have 5 pipes H/C/F/R and gas fairly close together which are running under a suspended timber floor on the ground floor. They are already insulated with really old pipe felt with plenty of uninsulated sections. I want to insulate them as best as possible and was thinking of using rockwool. I have started using cable ties but wondered is there a better way to insulate them and or is there a better way than cable ties to hold it in position.

I had also thought possibly of using bigger pipe foam but it doesn't fit well or even an old cylinder jacket.

Does anyone have any suggestions?

Thanks

 

[Masood]

Welcome to the forum nimh. Why not cut the old felt off and then use foam lagging?

 

[Best]

How tight are they together? You are best using pipe insulation of at least 19mm thick but you could use 9mm if you haven't space.
I was thinking you could perhaps case around the pipes also, but the gas pipe is something you would have to not go near, or enclose without a gas engineer advice

 

[Best]

Welcome to the forum nimh. Why not cut the old felt off and then use foam lagging?

I agree. Hair felt lagging is not much good and usually a serious fire risk.
It's too old fashioned even for me. Still remember wrapping new pipes with hair felt before putting them in place. Had to angle it, keeping it tight and overlapping it half way to double it, like a bandage. What a waste of time it was!

 

[nimh]

How tight are they together? You are best using pipe insulation of at least 19mm thick but you could use 9mm if you haven't space.

They are about 13mm apart so no chance of 19mm insulation

I was thinking you could perhaps case around the pipes also, but the gas pipe is something you would have to not go near, or enclose without a gas engineer advice

When you sat case around the pipes case with what?

I understand gas doesn't need insulating but is there reason for not insulating gas

 

[Best]

They are about 13mm apart so no chance of 19mm insulation

When you sat case around the pipes case with what?

I understand gas doesn't need insulating but is there reason for not insulating gas

You are probably not going to be able to get even 9mm thick pipe insulation on them, although the slightly more expensive black Armaflex 9mm is a rubber foam and will crush up better.
If you can't use anything else, then decent fireproof hair felt carefully double lapped will have to do. It has done for years and the good quality hair felt lasts.
I just mentioned casing pipes if it was a basement that you could easily get at the pipes to box them in with timber case and fill it with rock wool.
No point in insulating a gas pipe. Casing around it might be against regs but I am unsure and some of the gas plumbers could answer that.

 

[ShaunCorbs]

You are probably not going to be able to get even 9mm thick pipe insulation on them, although the slightly more expensive black Armaflex 9mm is a rubber foam and will crush up better.
If you can't use anything else, then decent fireproof hair felt carefully double lapped will have to do. It has done for years and the good quality hair felt lasts.
I just mentioned casing pipes if it was a basement that you could easily get at the pipes to box them in with timber case and fill it with rock wool.
No point in insulating a gas pipe. Casing around it might be against regs but I am unsure and some of the gas plumbers could answer that.

yes would be classed as in a void so would need ventilation, firebreaks etc

 

[gassafe]

Wrap it all in that bubble wrap type aluminium backed stuff

 

[snowhead]

Spiral Wrap 50mm x 7.5m | Pipe Insulation | NoLinkingToThis

Wrap it in a spiral along the pipes.

 

[Ric2013]

The oversold relective insulation. Spacemen use it in space so it must be good is the usual sales pitch I've heard.

Problem with that is that in space there is NO AIR. Without air there is no convection or conduction. Only radiation. So reflectives work brilliantly in a vacuum.

Back on earth, some felt wrap, old sweaters, recycled wool carpet underlay, rockwool, wool etc will probably work better for a given thickness than silvery bubble wrap. Plus they are cheap.