Open vent system...water pressure?

[martyc]

Hi there,
Have moved my boiler to a new location and now it refuses to fire up!
Before i plumbed the boiler i filled it with water to displace the air etc.
However im pretty sure there is still some air in the pipes etc. as when the pump starts up you can here it gurgling intermittently as air passes.
Could this be preventing the boiler from firing?
(is there a pressure sensor on open vent systems?)
The fan isnt even coming on...you can just hear contacts making when it is switched on.

Another thing is that the boiler is now higher up...id say there is only six or seven feet between it and the header tank...is this a sufficient head of pressure?
Many thanks,
Marty.

 

[chrishutt]

Sorry to pry into your private affairs, but could you consider possibly divulging the make and model of the boiler?

 

[martyc]

Thats Ok Chris!
Its an ideal classic NF50.
Cheers,
Martin.

 

[chrishutt]

Did you install the boiler in accordance with the manufacturer's instructions? In particular do you have an open vent pipe rising continuously from the boiler flow tapping to terminate over the feed & expansion tank?

 

[martyc]

Hi Chris,
I havent any MI's as its an old boiler i inherited when i bought the house!
The vent pipe does take a dip before it rises again...i have fitted an aav before it dips.
Marty.

 

[chrishutt]

It's essential to install according to the MIs (no apostrophe!). The falling vent pipe is potentially dangerous. Why don't you download a copy of the MIs from Ideal?

 

[martyc]

Hi Chris,
Point taken on the vent pipe...this is why i have fitted an aav directly above the boiler, and the intention is to take the dip out of it when i rip out the bath(pipework is behind it!)

Anyway...could this dip be causing it not to fire?
Could an airlock cause it not to fire?

I have looked for the MIs online but to no avail...ill try again.
Martin.

 

[Terrywookfit]

If you ask for advice and then choose to ignore it, why are you suprised when it does not work ??

 

[martyc]

I didnt choose to ignore any advice...im just looking for advice!!
It is not currently possible to avoid the dip in the pipework and somene recommended fitting aav's...so i did, now it aint firing and im just asking whether or not an open vented system requires pressure as a prerequisite to fire...ie does it check for pressure...the dip in the pipework does not change the pressure @ the boiler

 

[Terrywookfit]

In that case the answer is no!!

You still chose to ignore MI and take the advise that suited your needs though!!

It would have been a better plan to do your research before starting the job!!

 

[martyc]

Terry,
you stated in another thread that many installations are not to MI...and work anyway!

Anyway...i forgot to mention in that thread that on the side of boiler it says "this boiler is converted for use on a sealed system"...and if i read advice correctly on that thread this negates the need for a rise all the way to header tank?

Marty.

 

[Terrywookfit]

IF you have a sealed system then you do not have a header tank!!

This is replaced by a PRV and expansion vessell!!

As I said in a previous post you appear to be confused!!!

 

[martyc]

Terry, Im not confused...you are not reading my posts properly and assuming im confused!!
What i said was my boiler is capable of running on a sealed system...my system IS vented!!
Someone else said on another thread that the route of the vent (ie my dip) is not as important if the boiler is rated for a sealed system.
I dont know why this may or may not be the case but thats what someone advised.........

Because the boiler is capable of running on a sealed system im guessing it is looking for a certain amount of pressure before it will operate (failsafe)
Cheers,
Martin.

 

[Terrywookfit]

IF your boiler was converted for a sealed system it would have a pressure relief valve and vessell fitted!! Have you removed these or are they still fitted??
Is there a pressure gauge??
A prv would be a good thing with how yours is installed!!

I have on occasions found "Hybrid type systems" with a top up tank fed via a non return valve but these have never worked very well!!

This is why the appliance should be fitted to MI!!

 

[martyc]

Hi terry,
The boiler (as far as i know) was not converted but it is capable of running on a sealed system...i guess that means it is pressure rated and has other safety checks in built.

Someone said on another thread that if it is a sealed system compatible boiler that the vent setup i have would not be a problem?

The system IS open vented with a traditional F & E tank in the loft.

Is 6 foot heigth difference between header tank and boiler enough?...could this be why its not firing?

Cheers,
Marty.

EDIT:
it does have a 3 bar PRV fitted on top of boiler...no Vessel? though (i assume this is an expansion vessel you are referring to)