Heating pressure losing 0.7bar per 24 hours cycle.

Heatquest

I have an oil fired system, it's a 1960s bungalow with pipes in the screed. There's evidence from previous works ( a while ago) of pipes not being lagged/protected within the screed. 

The boiler has been isolated during which the pressure gauge moved down a very small amount in 36 hours. When the isolation valves were released a rush of water was heard entering the heating circuit and the gauge dropped 0.2/0.3 bar. Leak looks like the leak is greatest when the heating is on but still there when not.

I really don't want to replumb the heating ( both cost and disruption) but I think I could be chasing leaks one at a time for ever. Detailed investigation costs c£800 per go and this could go towards a permanent resolution to the buried pipes, albeit meaning surface mounted pipes.

I've not tried a leak sealer yet which another post has said doesn't last too long (2 weeks in their case).

Any ideas please? Is it best to accept a replumb is required or keep trying to trace and repair, if the leak can actually be found? 

ThisIsWeird

You've carried out the correct test, and it would appear pretty conclusive that the leak is outwith the actual boiler.

What a 'mare.

If you were to replumb, how would you run the new pipes? Could you do so behind hollow skirting boards? Or would you need to channel into the floor again?

I don't think anyone can speculate how well a find and fix repair will pan out, as the consensus I've read on here is, if one pipe has corroded through due to contact with concrete, others are likely to do so too.

FreeBear

ThisIsWeird said: I don't think anyone can speculate how well a find and fix repair will pan out, as the consensus I've read on here is, if one pipe has corroded through due to contact with concrete, others are likely to do so too.

A thermal imaging camera may reveal where a leak is. But digging up a concrete floor is going to be messy as well as disruptive. And as you say, once one pipe starts leaking, others will follow suit before too long. Unfortunately, wrong time of year to be pulling a heating system apart either to trace a leak or replumb. Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

Heatquest

FreeBear said:

ThisIsWeird said: I don't think anyone can speculate how well a find and fix repair will pan out, as the consensus I've read on here is, if one pipe has corroded through due to contact with concrete, others are likely to do so too.

A thermal imaging camera may reveal where a leak is. But digging up a concrete floor is going to be messy as well as disruptive. And as you say, once one pipe starts leaking, others will follow suit before too long. Unfortunately, wrong time of year to be pulling a heating system apart either to trace a leak or replumb. Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

FreeBear said:

ThisIsWeird said: I don't think anyone can speculate how well a find and fix repair will pan out, as the consensus I've read on here is, if one pipe has corroded through due to contact with concrete, others are likely to do so too.

A thermal imaging camera may reveal where a leak is. But digging up a concrete floor is going to be messy as well as disruptive. And as you say, once one pipe starts leaking, others will follow suit before too long. Unfortunately, wrong time of year to be pulling a heating system apart either to trace a leak or replumb. Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

FreeBear said:

ThisIsWeird said: I don't think anyone can speculate how well a find and fix repair will pan out, as the consensus I've read on here is, if one pipe has corroded through due to contact with concrete, others are likely to do so too.

A thermal imaging camera may reveal where a leak is. But digging up a concrete floor is going to be messy as well as disruptive. And as you say, once one pipe starts leaking, others will follow suit before too long. Unfortunately, wrong time of year to be pulling a heating system apart either to trace a leak or replumb. Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

FreeBear said:

ThisIsWeird said: I don't think anyone can speculate how well a find and fix repair will pan out, as the consensus I've read on here is, if one pipe has corroded through due to contact with concrete, others are likely to do so too.

A thermal imaging camera may reveal where a leak is. But digging up a concrete floor is going to be messy as well as disruptive. And as you say, once one pipe starts leaking, others will follow suit before too long. Unfortunately, wrong time of year to be pulling a heating system apart either to trace a leak or replumb. Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

Thanks. If it is replumbed as you suggest on 15/22mm pipe in anticipation of a heat pump in the future, how would that affect the use now with a standard oil boiler? Is it a question of re plumbing with either 15mm or 22mm throughout - and which would be better? We can't do cold so for a heat source system we'd seek the best heat output performance.

FreeBear

Heatquest said:

Thanks. If it is replumbed as you suggest on 15/22mm pipe in anticipation of a heat pump in the future, how would that affect the use now with a standard oil boiler? Is it a question of re plumbing with either 15mm or 22mm throughout - and which would be better? We can't do cold so for a heat source system we'd seek the best heat output performance.

Won't make the slightest difference if used with an existing boiler. That said, if the boiler is a condensing model (mandatory if installed April 2005 or later), bigger pipes coupled with larger radiators means you can run at a lower flow temperature which will boost efficiency. You may even find that the system is quieter when the circulation pump is running.

I replumbed my heating system two years ago, using 22mm for the main feed/return pipes and 15mm tails to the radiators. Pipes were routed with a heat pump in mind even although I was installing a gas boiler. When the time comes for a heat pump, I'll (probably) need to run a short length of 28mm for the final connection.

Belenus

FreeBear said:

 Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

Are plastic pipes recommended now?

Our 2004 built house has mainly plastic pipework for the CH system.

FreeBear

Belenus said:

FreeBear said:

 Personally, I'd bite the bullet and go for a replumb, fitting larger radiators (and use 15/22mm pipe) with an eye to installing a heat pump at some point in the future.

Are plastic pipes recommended now?

Our 2004 built house has mainly plastic pipework for the CH system.

Not in my book, and I'd steer well clear of Speedfit type joins... One thing to bear in mind with plastic pipe & fittings is the bore is quite a bit smaller than the equivalent copper pipe. This will restrict the volume of water that can be circulated around the system and thus the amount of heat distributed to each radiator. You can increase the pump speed to compensate, but this increases noise and places a greater strain on the pump.

House builders like plastic pipe because it is cheap and quick to install. And they don't have to worry about it lasting..

ThisIsWeird

Nothing wrong with plastic pipe
Apart from the narrower bore - fair point. But if 22mm is used extensively, with only short runs - tails - to each rad, there should be no problem. If it's a larger circuit, you can even consider 28mm for at least part of the main run. But, in essence, the plumber will choose their preferred system.
In fact, had plastic pipe been fitted originally, you wouldn't have your current corroded-copper issue

Albermarle

I used to have some contact in my job with plastic pipe manufacturers and in areas where plastic pipe competed with other materials. Also where one type of plastic competed with another type.
If you asked the question what is actually the best material for any application, ( could be for gas, water, heating, waste etc ) there was a plethora of competing opinions and commercial interests. Different standards in different countries complicated matters as well ( little EU wide integration in this area).
Also architects, builders, plumbers etc can be very conservative in adopting new materials and practices.

Are plastic pipes recommended now?

So the answer to this question is 'it depends' 

FreeBear

ThisIsWeird said: Nothing wrong with plastic pipe

The fittings are big ugly things, and the inserts restrict flow even further.

Whilst it is possible to use copper on the final ~200mm to the radiators, you still need space to accommodate those ugly fittings.

ThisIsWeird

FreeBear said:

ThisIsWeird said: Nothing wrong with plastic pipe

The fittings are big ugly things, and the inserts restrict flow even further.

Whilst it is possible to use copper on the final ~200mm to the radiators, you still need space to accommodate those ugly fittings.

Yup, that's true :-)