Nightmare Airlock

[Mbear]

I'm havin a bit of a mare as the title suggests with an open system airlock.

The boiler is a 28cdi w/Bosch set up on a open vent rather than a pressurised system. I had to do a full drain down to replace hw diaphragm which wasn't the easiest to start with, rebuild boiler and fill/vent system, no leaks-perfect Or so I think. Turn heating on, starts overheating.

So far I've tried

1. Open draincock with the tank still filling in an effort to force the air out that way. No joy
2. Drained completely, refilled and vented. No joy
3. Changing the pump speed (1 through 3) while heating is running to try force the air/bubbles up the open vent. No joy
4. Used the internal boiler fill loop to try force the water/air up the way. No joy.

I'm at my wits end with this system, it's still overheating. I may change the pump 2moro maybe, but I've decided to try back fill the system through the draincock from a tap when I go back. As I say though any suggestions are appreciated.

Ps anyone got a rope and a stool they are not using? Lol

 

[Plumbstar Tom]

was going to say whack a hose on a drain cock but thats what your trying any way

 

[Puddle]

Some alternatives

cap off vent and place closed gate valve on cold feed,turn boiler stat down,pressurise to a couple of bar,through internal filling loop,,run,hopefully clear,remove cap and open gate valve and cut off spindle
or
fit gate valve on flow or return near boiler and a tee piece with 15mm ball a fix valve underneath gate valve,refill,close gate valve and attach hose to ball a fix valve open internal filling loop and flush though round system
or
normally would also suggest fit gate valves on flow and return under boiler and turn pump round,once cleared isolate and it pump correct way round but think on some models expansion vessel pipe work attached
imho

 

[Mbear]

Some alternatives

cap off vent and place closed gate valve on cold feed,turn boiler stat down,pressurise to a couple of bar,through internal filling loop,,run,hopefully clear,remove cap and open gate valve and cut off spindle
or
fit gate valve on flow or return near boiler and a tee piece with 15mm ball a fix valve underneath gate valve,refill,close gate valve and attach hose to ball a fix valve open internal filling loop and flush though round system
or
normally would also suggest fit gate valves on flow and return under boiler and turn pump round,once cleared isolate and it pump correct way round but think on some models expansion vessel pipe work attached

do u think It would work if I had one of the other engineers hold a 'plumbers mate bung' in the cold feed while I fill via fill loop and vent rads as quick as I could that this may work instead of the extra hassle of fitting a gate valve on the cold feed?

Ps there is no open vent. It's a cold feed only setup.
just to paint a better picture for u.
I think an open vent would have helped me if it was fitted originaly

 

[Puddle]

Sorry use to working by my self,he should be able to hold bung in,however the idea is to run system under pressure for a while

fitting a valve does not take long,pipe slice bosh,bosh

Above ways I have mention,people say,oooh,fitting valves,reversing pump,to much work,then go spend ages trying to back fill ect but above works do not take long

Hope you left pump running over night,my have cleared by morning

 

[fuzzy]

persevere, youll get it in the end

 

[Mbear]

Sorry use to working by my self,he should be able to hold bung in,however the idea is to run system under pressure for a while

fitting a valve does not take long,pipe slice bosh,bosh

Above ways I have mention,people say,oooh,fitting valves,reversing pump,to much work,then go spend ages trying to back fill ect but above works do not take long

Hope you left pump running over night,my have cleared by morning

no turned it off, wanted it cold for this morn, to start fresh.
My other thought is it may not be airlocked and it's simply the geanoni valve rear spring isn't movin causing this overheat.
I'll find out soon

 

[Billy Bob Bob]

dont over look the aav in the boiler,it may have stuck causing the over heat

 

[Mbear]

dont over look the aav in the boiler,it may have stuck causing the over heat

It's open vented mate, ie aav is not fitted-instead the original installer has made it open vented.

I tried the hw 1st thing while it was still cold this morn(it overheated) as it's overheating using the internal primary circuit only for hw then I'm gona replace the full DV. Seems like the only option seeing as the boiler is full of water. It obviously overheated in ch mode aswell. Any1 ever had this b4?

 

[Billy Bob Bob]

so its a open vent combi,even so it should have a aav on the heat exchanger,you would expect it to vent up and over but they dont always,i would look at the heat exchanger,if theres a aav,you know what to do,i take it theres water in the system and rads are full etc

 

[Mbear]

so its a open vent combi,even so it should have a aav on the heat exchanger,you would expect it to vent up and over but they dont always,i would look at the heat exchanger,if theres a aav,you know what to do,i take it theres water in the system and rads are full etc

ye I got a slight bit of circulation/heat this morning in the rads but not all the rads. Once I replace the DV on Monday and while the system is empty I'm gona fit an aav on flow&return on the highest points I can find to aid the refill this time. I'm pretty confident(fingers crossed)that when I do this lot then it'll fill nicely and work pretty much straight away. If not then I'll defo need that rope and stool I ask for earlier lol

 

[Billy Bob Bob]

pain in the ar** when systems do this

 

[Mbear]

pain in the ar** when systems do this

It always makes me wonder..... How in gods name did the original installer fill this bloody thing, it feels as if they go out of there way to make it a nitemare for future draindown refill repairs. I can see no reason why this was not fitted as a pressurised system originaly, this water pressure is very strong in the house/general area. The mind boggles, it really does!!!!

 

[Mbear]

Update on this job....

Drained chb&sys completely.
Replaced the full geannoni diverter valve along with numorous o-rings.
Replaced pumphead.
Fit aav on highest return point I could get.
Refilled/vented and hoped for the best.

In operation the 1st couple of times it overheated, vented all again whilst ch was on. Got it circulating finally, spent more time venting pump/rads.

I don't think it's 100% quite right(fully vented)yet but it's working now.
So it seemed to work, I'll find out 2moro after the cust vents rads again in the morn if it's spot on or of more works reqd.

Fingers crossed that's it finished