Open vent issue

sitja

Hi was looking at a central heating system, Its an old potterton prima f boiler but the f&e header tank in the attic has no vent pipe and the feed from it is in 15MM...?? Is this totally wrong??

sitja

here is a sketch of what im talking about..

anthonyos

is there a problem ???i dont think there is anything wrong

Billy Bunting

I dont really understand your diagram but if we're talking combined cold feed and vent then it should be 3/4 pipe.

sitja

No the system is drained down now, but im wondering about when filling it back up will it give me trouble... Why is there no vent?? I thought being open vented it would need to be vented or atleast combined feed & vent and i thought that needed to be 22mm..?

sitja

Billy Bunting wrote: »

I dont really understand your diagram but if we're talking combined cold feed and vent then it should be 3/4 pipe.

What dont you understand?? And i will try break it down... and i was thinking the same if it was combined..

anthonyos

are you a plumber??

spireland32

If there's no vent pipe there must be a vessel somewhere... Under the floor, under the stairs, in a press could be anywhere. Is there a nrv on the cold supply?

Billy Bunting

spireland32 wrote: »

If there's no vent pipe there must be a vessel somewhere... Under the floor, under the stairs, in a press could be anywhere. Is there a nrv on the cold supply?

spireland32

Billy Bunting wrote: »

what do you not understand?
if theres no vent pipe it must be a closed system and a pressure vessel must be located somewhere in the house.... get me?

Sorry just read that back billy... sound like a w@nker. didnt mean to come across like that

anthonyos

spireland32 wrote: »

what do you not understand?
if theres no vent pipe it must be a closed system and a pressure vessel must be located somewhere in the house.... get me?

but does the op understand ???going into detail like this can be a waste of time typical diyer incompetence

spireland32

sitja wrote: »

No the system is drained down now, but im wondering about when filling it back up will it give me trouble... Why is there no vent?? I thought being open vented it would need to be vented or atleast combined feed & vent and i thought that needed to be 22mm..?

why do you think its opened vented? Because the boiler is old? The prima can be used on a closed/sealed system.

Billy Bunting

spireland32 wrote: »

what do you not understand?
if theres no vent pipe it must be a closed system and a pressure vessel must be located somewhere in the house.... get me?

Sorry, but have you ever heard of a combined cold feed and expansion pipe.

sitja

spireland32 wrote: »

sitja wrote: »

No the system is drained down now, but im wondering about when filling it back up will it give me trouble... Why is there no vent?? I thought being open vented it would need to be vented or atleast combined feed & vent and i thought that needed to be 22mm..?

why do you think its opened vented? Because the boiler is old? The prima can be used on a closed/sealed system.

I have good plumbing experience but not to much domestic.. All pipework in house is exposed so im sure there is no vessel.. it aint sealed.. the system is as the sketch is really.. there was previously a back boiler but that has been disconnected from system.

spireland32

Billy Bunting wrote: »

Sorry, but have you ever heard of a combined cold feed and expansion pipe.

Of course... but the OP said there was NO vent pipe in the attic. A common cold feed and expansion would/should be 3/4, as you said, off the top of flow pipe on the coil up into the attic. Spilt 1/2 into the tank for the fill and continue 3/4 up and over the tank for a vent.

Billy Bunting

spireland32 wrote: »

Of course... but the OP said there was NO vent pipe in the attic. A common cold feed and expansion would/should be 3/4, as you said, off the top of flow pipe on the coil up into the attic. Spilt 1/2 into the tank for the fill and continue 3/4 up and over the tank for a vent.

So presumably if the 1/2 cold feed was an undersized feed and vent pipe that would mean it may well not be a sealed system.

As i said on post1 the diagram is vaige.

Incidentally, it doesnt need to split and vent over the tank.

sitja

Billy Bunting wrote: »

spireland32 wrote: »

Of course... but the OP said there was NO vent pipe in the attic. A common cold feed and expansion would/should be 3/4, as you said, off the top of flow pipe on the coil up into the attic. Spilt 1/2 into the tank for the fill and continue 3/4 up and over the tank for a vent.

So presumably if the 1/2 cold feed was an undersized feed and vent pipe that would mean it may well not be a sealed system.

As i said on post1 the diagram is vaige.

Incidentally, it doesnt need to split and vent over the tank.

Yes im aware of a combined system but it being a half inch pipe made me think something is wrong. and i am wondering is this safe if it is a combined system and the pipe is half inch..

spireland32

Billy Bunting wrote: »

So presumably if the 1/2 cold feed was an undersized feed and vent pipe that would mean it may well not be a sealed system.

As i said on post1 the diagram is vaige.

Incidentally, it doesnt need to split and vent over the tank.

Suppose it doesnt need to spilt but i have never seen one not. Unlikely not to have a vent up and over IF it is an open system. It could be over the domestic tank seen that loads of times. In fairness it could be anything and we're only guessing at this stage! open, closed, vessel, vent, non return, common cold feed and expansion.... Put the kettle on

spireland32

sitja wrote: »

Yes im aware of a combined system but it being a half inch pipe made me think something is wrong. and i am wondering is this safe if it is a combined system and the pipe is half inch..

Best get a domestic plumber to have a quick look if your not sure.

Billy Bunting

sitja wrote: »

Yes im aware of a combined system but it being a half inch pipe made me think something is wrong. and i am wondering is this safe if it is a combined system and the pipe is half inch..

IF it is a combined feed and vent (it does seem a possibility) then in 1/2 then yes, it is very dangerous, cold feeds block regulary, if yours blocks you have a presure cooker.

Suppose it doesnt need to spilt but i have never seen one not. Unlikely not to have a vent up and over IF it is an open system.

I'm sure Mr Google will show you a few examples,,,,,,,, http://www.google.com/imgres?q=combined+feed+and+vent+pipe&hl=en&sa=X&rls=com.microsoft:en-ie:IE-SearchBox&rlz=1I7ACAW_enIE398&biw=887&bih=423&tbm=isch&prmd=imvnsfd&tbnid=o0Sj8aBjUTHw5M:&imgrefurl=http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2675/I44-2675/I44-2675.htm&docid=iSUH9N4-n0fOqM&imgurl=http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2675/I44-2675/I44-2675-015.gif&w=235&h=228&ei=oYbjT8y8B4WBhQfi-8TbAw&zoom=1

spireland32

Mr Google :):)..... Thats a UK way of doing it (i am not a racist, i love black people)

sitja

Billy Bunting wrote: »

sitja wrote: »

Yes im aware of a combined system but it being a half inch pipe made me think something is wrong. and i am wondering is this safe if it is a combined system and the pipe is half inch..

IF it is a combined feed and vent (it does seem a possibility) then in 1/2 then yes, it is very dangerous, cold feeds block regulary, if yours blocks you have a presure cooker.

Suppose it doesnt need to spilt but i have never seen one not. Unlikely not to have a vent up and over IF it is an open system.

I'm sure Mr Google will show you a few examples,,,,,,,, http://www.google.com/imgres?q=combined+feed+and+vent+pipe&hl=en&sa=X&rls=com.microsoft:en-ie:IE-SearchBox&rlz=1I7ACAW_enIE398&biw=887&bih=423&tbm=isch&prmd=imvnsfd&tbnid=o0Sj8aBjUTHw5M:&imgrefurl=http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2675/I44-2675/I44-2675.htm&docid=iSUH9N4-n0fOqM&imgurl=http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2675/I44-2675/I44-2675-015.gif&w=235&h=228&ei=oYbjT8y8B4WBhQfi-8TbAw&zoom=1

See thats the only pipework going to attic.. Storage tank is downstairs aswell as dhw cylinder.. was just hoping others witnesed this an had advice.. See the system is drained and i never seen it work but im to assume it worked for previous users..

aujopimur

Your system is what's known as semi sealed, it was acceptable once upon a time.
I would'nt consider it dangerous, the easiest way to to bring it up to spec is to fit an expansion vessel on the boiler flow before any valves or pump.

sitja

sitja wrote: »

Billy Bunting wrote: »

sitja wrote: »

Yes im aware of a combined system but it being a half inch pipe made me think something is wrong. and i am wondering is this safe if it is a combined system and the pipe is half inch..

IF it is a combined feed and vent (it does seem a possibility) then in 1/2 then yes, it is very dangerous, cold feeds block regulary, if yours blocks you have a presure cooker.

Suppose it doesnt need to spilt but i have never seen one not. Unlikely not to have a vent up and over IF it is an open system.

I'm sure Mr Google will show you a few examples,,,,,,,, http://www.google.com/imgres?q=combined+feed+and+vent+pipe&hl=en&sa=X&rls=com.microsoft:en-ie:IE-SearchBox&rlz=1I7ACAW_enIE398&biw=887&bih=423&tbm=isch&prmd=imvnsfd&tbnid=o0Sj8aBjUTHw5M:&imgrefurl=http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2675/I44-2675/I44-2675.htm&docid=iSUH9N4-n0fOqM&imgurl=http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2675/I44-2675/I44-2675-015.gif&w=235&h=228&ei=oYbjT8y8B4WBhQfi-8TbAw&zoom=1

See thats the only pipework going to attic.. Storage tank is downstairs aswell as dhw cylinder.. was just hoping others witnesed this an had advice.. See the system is drained and i never seen it work but im to assume it worked for previous users..

Are you a plumber billy..

Billy Bunting

sitja wrote: »

Are you a plumber billy..

No!! Do you need a plumber ??

sitja

Billy Bunting wrote: »

sitja wrote: »

Are you a plumber billy..

No!! Do you need a plumber ??

I only seen the comment semi sealed there.. if it is semi sealed.. how did it expand previously.. I was just wondering was my sketch that bad that a plumber couldnt understand..

spireland32

What storage tank is downstairs?

sitja

spireland32 wrote: »

What storage tank is downstairs?

The storage cistern for sink and toilet.. no toilet or plumbing other than heating upstairs..

spireland32

sitja wrote: »

spireland32 wrote: »

What storage tank is downstairs?

The storage cistern for sink and toilet.. no toilet or plumbing other than heating upstairs..

This is getting confusing! What does this storage tank look like? Is there only the f&e tank in the attic? No other tank?

Better off get a mate of yours in domestic heating to throw on eye on it for you if you feel it's unsafe. Really need to see it to give a definite answer.

sitja

Yup thats all thats in attic... Plumbing is crazy throughout the house... will try take a few pics if im there tommorrow... Basically attic has main to feed expansion tank, 1/2 cold feed from it and then a 3/4 overflow. will try enhance my sketch a bit better so you guys can try get the idea... I Am really just considering close coupling it before the pump on the flow.

But was curious to know was the set up ok as it was.. But obviously not... My only conclusion is that it was a combined feed & vent but was undersized and should of been 3/4 pipe.

Oh and storage tank looks like any other standard house plastic tank..

sitja

I tried to make drawing a bit better for you guys to understand but still pretty much the same, I also put in the design I would change to if acceptable, those are the yellow and purple lines.... the black line (cold feed) would be rerouted to tie in next the boiler and not where its seen tied in earlier in the sketch..

dave12345

Just seen this post on diynot forum, there a shower of w**kers the real pros are on this forum:D

sitja

dave12345 wrote: »

Just seen this post on diynot forum, there a shower of w**kers the real pros are on this forum:D

Ah i wouldn say that... they cant be helpful too.. all different opinions can be helpful and hopefully some others have seen this sort of design..

JohnnieK

Why dont you just seal it properly and be done? It would also be cheaper than running a new vent pipe back up to the tank.

aujopimur

JohnnieK wrote: »

Why dont you just seal it properly and be done? It would also be cheaper than running a new vent pipe back up to the tank.

It's not a good idea to seal old systems, they usually leak when pressurised.
As I said in a previous post, an expansion vessel is all it needs

JohnnieK

aujopimur wrote: »

It's not a good idea to seal old systems, they usually leak when pressurised.
As I said in a previous post, an expansion vessel is all it needs

If all the pipework is exposed as stated I wouldn't be afraid to seal it. By putting a vessel on, it will be sealed then too.

aujopimur

I never suggested sealing it, only to fit an expansion vessel at the boiler.

JohnnieK

The vessel will only come into play if the f&e pipe ever becomes blocked. I would sooner seal it as all pipework is exposed. I have sealed loads of open systems without any drama.
The easier option by the sounds of it would be to increase the diameter of the f&e pipe to 3/4" and it would be up to specs then. It sounds like a short enough run.

JohnnieK

aujopimur wrote: »

I never suggested sealing it, only to fit an expansion vessel at the boiler.

Apologies, never read the post properly. Had a few last night.

sitja

JohnnieK wrote: »

aujopimur wrote: »

I never suggested sealing it, only to fit an expansion vessel at the boiler.

Apologies, never read the post properly. Had a few last night.

Isnt fitting the vessel basically lile sealing it though.. Well semi sealed!!!!

JohnnieK

sitja wrote: »

Isnt fitting the vessel basically lile sealing it though.. Well semi sealed!!!!

Not really because the f&e pipe is still open unless you put a non-return valve on it too.

JohnnieK

sitja wrote: »

Isnt fitting the vessel basically lile sealing it though.. Well semi sealed!!!!

What did you do in the end?