seal open vented system

brando75

hI ALL. I HAVE 25 YEAR OLD OIL CENTRAL HEATING SYSTEM. OPEN VENTED.. AM THINKING ABOUT SEALING SYSTEM. FROM WHAT I'VE READ THERE COULD BE A PROBLEM WITH LEAKS WHEN CHANGE OVER TAKES PLACE. DOES ANYONE HAVE EXPERIENCE OF THIS?? AM I IN FACT BETTER OFF SEMI SEALING WITH FEED STILL FROM HEADER TANK?? plumber says pressurizing system will not cause leaks but may show up leaks which are already there.. any advice please greatly appreciated

sullzz

Your plumber is correct although you will be increasing the pressure into the system , you could tie up your ballcock in your f+e cistern and mark the water line and monitor it over a couple of days to see if you are losing water , why do you want to seal your system anyway

shane0007

As long as you do not wish to put solid fuel into it in the future, I would always go with a pressurised system. More pressure = more force = more heat. If I had a weak system, I would prefer to know the weaknesses and deal with them.

corkgsxr

it can cause leaks.

your going from .3-.4 bar at best to 1-1.5 bar

stuff that might have leaked in a year or so will prob leak now

brando75

I am sealing system as expansion is over flowing into header tank. I've discovered here on a previous thread that this is happening because feed from expansion tank is fed into return in hot press and pump in boiler house is on return thus sucking water constantly from header tank. To combat this another guy put a handle valve on flow into cylinder and when i turn this on three quarters the expansion stops over flowing but rads downstairs then stop heating properly.. I want to seal as this seems like a permanent proper fix to my problem or would you consider semi sealing in my case... and yes i've noticed the header tank does lose water.. is this due to a leak somewhere in the system??? could there be any other reason?

shane0007

corkgsxr wrote: »

it can cause leaks.

your going from .3-.4 bar at best to 1-1.5 bar

stuff that might have leaked in a year or so will prob leak now

The increase in pressure does not cause leaks. The poor fittings do.

corkgsxr

shane0007 wrote: »

The increase in pressure does not cause leaks. The poor fittings do.

normally you wouldnt get big leaks. but you can get fitting start to drip. or maybe they were a tiny seep before and with the extra pressure they start to drip

you dont know how good or bad someones elses work is

TPM

IMO part of the reason people say that pressurising a system causes leaks is due to the fact that before the system was pressurised the leaks were not noticed.
This is due to a few reasons,
The increased pressure increases the volume that is leaking out of an existing leak making it more obvious.

After pressurising a system people expect leaks and tend to look for them thus finding ones that were always there.

Alot of systems loose water through leaks but when this is constantly replaced by the ball cock in the expansion tank it isnt noticed but when the system is pressurised and the fill loop is disconnected the pressure loss is not replaced and the system then performs poorly of not at all, again making previously unknown leaks very obvious.

Saying pressurising a system causes leaks is like saying power flushing causes leaks, they dont cause leaks they only show up problems that already existed

shane0007

TPM wrote: »

IMO part of the reason people say that pressurising a system causes leaks is due to the fact that before the system was pressurised the leaks were not noticed.
This is due to a few reasons,
The increased pressure increases the volume that is leaking out of an existing leak making it more obvious.

After pressurising a system people expect leaks and tend to look for them thus finding ones that were always there.

Alot of systems loose water through leaks but when this is constantly replaced by the ball cock in the expansion tank it isnt noticed but when the system is pressurised and the fill loop is disconnected the pressure loss is not replaced and the system then performs poorly of not at all, again making previously unknown leaks very obvious.

Saying pressurising a system causes leaks is like saying power flushing causes leaks, they dont cause leaks they only show up problems that already existed

That's exactly what I was trying to say but just much better put!

aujopimur

Why not make it a semi sealed system, disconnect the existing cold feed and use the expansion as your new cold feed.

Dtp79

aujopimur wrote: »

Why not make it a semi sealed system, disconnect the existing cold feed and use the expansion as your new cold feed.

When you say use the expansion are you referring to the vent?

shane0007

I personally do not see the value of a semi-sealed system. No gain in pressure and they still hide leaks. If I had a leak or even a weap, I would rather know about it and sort it.

brando75

I'm not sure i ned extra pressure as i just want to stop the pitching problem. On the other hand if leaking already why not find and fix.

If i am to seal could you please explain what work is involved as i want to make sure plumber is doing it properly. Had a few cowboy boys and still same problems. Is this a straight forward enough or complicated job.

shane0007

It is a very simple job. Remove & blank the osvp & the f & e pipe. Tee in mains supply with a flexible filling loop. Install a pressure gauge & expansion vessel sized according to the volume of water within your heating system, i.e. 11%.

If you do not wish to discover wet leaks, drain the system, do all of the above works but fill the system to 2 bar pressure with air. Leave stand for a couple of hours to monitor any pressure drop, if no drop, fill with water.

TPM

brando75 wrote: »

hI ALL. I HAVE 25 YEAR OLD OIL CENTRAL HEATING SYSTEM. OPEN VENTED.. AM THINKING ABOUT SEALING SYSTEM. FROM WHAT I'VE READ THERE COULD BE A PROBLEM WITH LEAKS WHEN CHANGE OVER TAKES PLACE. DOES ANYONE HAVE EXPERIENCE OF THIS?? AM I IN FACT BETTER OFF SEMI SEALING WITH FEED STILL FROM HEADER TANK?? plumber says pressurizing system will not cause leaks but may show up leaks which are already there.. any advice please greatly appreciated

brando75 wrote: »

I'm not sure i ned extra pressure as i just want to stop the pitching problem. On the other hand if leaking already why not find and fix.

If i am to seal could you please explain what work is involved as i want to make sure plumber is doing it properly. Had a few cowboy boys and still same problems. Is this a straight forward enough or complicated job.

Just a quick question.
Has the system been pitching for 25years?
If not (and I would guess it hasnt been) something has changed to cause this to happen, changed circulating pump? pipework change? boiler change?
If not you could have sludge/blockage causing the pitching.
You really need to resolve the problem first

aujopimur

Dtp79 wrote: »

When you say use the expansion are you referring to the vent?

Yes.

aujopimur

shane0007 wrote: »

I personally do not see the value of a semi-sealed system. No gain in pressure and they still hide leaks. If I had a leak or even a weap, I would rather know about it and sort it.

His problem is pitching, not leaks.

Dtp79

aujopimur wrote: »

Yes.

The vent isn't the expansion pipe. The vent is the vent. The " cold feed " is the expansion pipe

brando75

The pitching problem started after i disconnected the old back boiler from the system. I'm only here 6 years and as far as i know it wasn't always pitching.

Ok, i have another inquiry. At the moment my flow and return from boiler go into kitchen halfway up wall then straight upstairs into kitchen ceiling across bedroom floor and are teed into flow and return from hot press under another bedroom floor. A plumber has suggested blanking these pipes at kitchen ceiling and running them straight into flow and return behind fireplace. Is there any value in doing this?? apart from hiding them from view!! Downstairs rads at the moment do not heat great as upstairs is getting done first.. Would anyone foresee that leaving these blanked pipes under floor of bedroom is big waste or not?? thanks in advance for all answers

TPM

brando75 wrote: »

The pitching problem started after i disconnected the old back boiler from the system. I'm only here 6 years and as far as i know it wasn't always pitching.

Ok, i have another inquiry. At the moment my flow and return from boiler go into kitchen halfway up wall then straight upstairs into kitchen ceiling across bedroom floor and are teed into flow and return from hot press under another bedroom floor. A plumber has suggested blanking these pipes at kitchen ceiling and running them straight into flow and return behind fireplace. Is there any value in doing this?? apart from hiding them from view!! Downstairs rads at the moment do not heat great as upstairs is getting done first.. Would anyone foresee that leaving these blanked pipes under floor of bedroom is big waste or not?? thanks in advance for all answers

IMO there is a fair bit more to this than just making the system pressurised and or re-routing the flow and return for the boiler.
to get the best out of your system you need to get a plumber in, the flow and return need to be piped to allow zoning, powerflushing is likely to be required then you can consider pitching. If there were no problems with the system it wouldnt be pitching

brando75

But i know why it is pitching.. because pump is on the return and cold feed is piped into return from header tank.. this is causing it to pitch

Dtp79

brando75 wrote: »

But i know why it is pitching.. because pump is on the return and cold feed is piped into return from header tank.. this is causing it to pitch

That's not a problem if its piped into the correct place on the return. As long as its in front of the pump then it will work fine

TPM

brando75 wrote: »

But i know why it is pitching.. because pump is on the return and cold feed is piped into return from header tank.. this is causing it to pitch

The problem is that the boiler and pump were just piped into the existing solid fuel system, the pump was put on a pipe and it appeared to work. if it had been installed correctly it would not be pitching as Dtp said.
if you blank off the feed/expansion pipe and vent pipe it will prevent the pitching, but this still does not mean the system is working properly.