One pipe system .... questions

[Old man Jim]

Bought a 1960's Bungalow back in 2002 ...which came equipped (fitted by BG back in 1995) as follows :

One pipe system (3/4" & 22mm) comprising of :
Ideal 60N e type free standing gas boiler in Garage
10 radiators , all fitted with Danfoss TRVs
SMC 24 hour Timer/ clock /controller
SMC Commodore 3 port controller ( I even have a brand new spare one of these in the box , ready to replace when it goes)
Grundfos 2 port pump
Hot water cylinder in airing cupboard
Cold water tank & F&E tank(vented) in loft
3 no. Brass air vent caps in loft

The system works fine ...and appears to have been thought out quite well .......even the last radiator on the circuit is sited in the Kitchen which is also on the warmest , south facing elevation , so isn't an issue when the rad is last to warm up.

Over the years I've been lucky enough to have two really good old school plumbers to call upon ......they both gave the same advice "If you can , try and keep the Boiler you have ..... it's the Rolls Royce of Boilers"
* Unfortunately they have both now retired

On the odd occasion that servicing work was required ...such as re-siting a radiator, or preventative flushing of the system or changing a stuck valve .....here are the only issues they encountered and I wondered if you guys could offer any solutions :

Danfoss TRVs .....every start up after summer, I have to remove the TRV heads and tease /oil the pin back out ......
Would really like a solution instead of having to do it every year.


Every time the system is drained , it takes an age to purge the air from the main 22mm
flow/return pipe .The only proven solution has been to purge the air via the three air vent caps situated at the highest point of the system ..in the loft .....and then it takes an age as only a small amount of air is released, whereupon you have to circulate the system ...then purge some more air ...and so on . The last occasion took 4 hours to get the air out !

Would an air separator ? or perhaps a bottle vent work to get the air out automatically ?

 

[SimonG]

System sounds dirty. That's why the pins are sticking on the Trv's. Get some inhibitor in it and maybe a magnetic filter.

 

[townfanjon]

It probably was the Rolls Royce of boilers then Jim , but it is not now believe me , modern boilers have plenty energy saving controls these days, however you have to answer the question do I spend a few grand on installing a new boiler to save probably around 20 ish % of gas lol .

 

[EvilDrPorkChop]

Danfoss TRVs ...every start up after summer, I have to remove the TRV heads and tease /oil the pin back out ..
Would really like a solution instead of having to do it every year.

Leave them fully open in summer rather than closing them. Works every time.

The little pins are problematic I find, even on clean systems. If the valves are old maybe worth replacing them at some point.

 

[Roy_66]

For the vents you can get automatic ones, however I'm not sure how long they are good for, perhaps post that as a question, if the pros don't spot this. I'm also wondering if one of the manual vent valves could be inverted so it dribbles into a tun dish, with waste to outside, so you could leave that dribbling until all the air is out. Would need the waste pipe for that to be large enough bore. If on your own a couple of phones with Skype or Zoom would show you what is going on I the loft.

Other question, does your boiler thermo have a setting so you can run the pump with no heat on to first get most of the air out. Alternative would be a hotwire switch for the pump ( not sure if anybody has done that ).

Cheers,

Roy ( very amateur plumber )

 

[Old man Jim]

System sounds dirty. That's why the pins are sticking on the Trv's. Get some inhibitor in it and maybe a magnetic filter.

To be fair to the 2 Plumbers .....good, honest , tradesmen who know their stuff...especially older systems like mine , the system has been well maintained ....boiler serviced every year.....each time the system was drained down the water was clear .....inhibitor used at least twice in the 18 years I've lived in the house ....I also know of 4 radiators that had to be moved ..only from one wall to another in the same rooms and each of them were taken outside and flushed out with a hosepipe before re-siting.
[automerge]1590347316[/automerge]

It probably was the Rolls Royce of boilers then Jim , but it is not now believe me , modern boilers have plenty energy saving controls these days, however you have to answer the question do I spend a few grand on installing a new boiler to save probably around 20 ish % of gas lol .

I get what you're saying and you're absolutely right........if the boiler packed up tomorrow I'd have no choice but to replace the boiler ....I don't mind that, it's had a good life ....and I would then probably have the one pipe system converted to the regular two pipes .......not so bad on a bungalow .....except for all the redecorating .....and the vertical pipe runs which we don't have at the moment.
* And to be honest , I'm not a big fan of Combi boilers.
[automerge]1590348101[/automerge]

For the vents you can get automatic ones, however I'm not sure how long they are good for, perhaps post that as a question, if the pros don't spot this. I'm also wondering if one of the manual vent valves could be inverted so it dribbles into a tun dish, with waste to outside, so you could leave that dribbling until all the air is out. Would need the waste pipe for that to be large enough bore. If on your own a couple of phones with Skype or Zoom would show you what is going on I the loft.

Other question, does your boiler thermo have a setting so you can run the pump with no heat on to first get most of the air out. Alternative would be a hotwire switch for the pump ( not sure if anybody has done that ).

Cheers,

Roy ( very amateur plumber )

Thanks Roy .....yes, I was thinking of replacing the knurled brass air vent caps with auto air vents ....both are 1/8" BSP , so just need the appropriate brass coupling to connect up .....should then automatically let air out .....just not sure how long it would take!
The boiler thermostat can be switched off , so yes I should think I could run the pump .....and if push comes to shove , I could easily hot wire it if I needed to.
Still not sure though if a bottle valve or air separator would work better ?

 

[SJB060685]

I'm also wondering if one of the manual vent valves could be inverted so it dribbles into a tun dish, with waste to outside, so you could leave that dribbling until all the air is out.

That would not work as air is less dense than water and would only sit at the top.

 

[Roy_66]

That would not work as air is less dense than water and would only sit at the top.

T off up then down to the valve, and keep the vent valve above the main pipe (manual valve) is what I'm imagining. Perhaps I'm not visualising something right. Valve would be upside down (for the collection tun). Might well be a better neater way.
[automerge]1590393834[/automerge]

T off up then down to the valve, and keep the vent valve above the main pipe (manual valve) is what I'm imagining. Perhaps I'm not visualising something right. Valve would be upside down (for the collection tun). Might well be a better neater way.

Or better still:

(Only one of these) T off the pipe where the air collects the worst, go up, elbow to left or right to get off the line of the pipe, then into T to go up to an auto vent valve, and down to a manual vent valve placed over a tun dish (funnel) with waste to outside (ideally visible flow outside). The manual valve is just to be cracked open for filling the system. All that has to be lower than the header tank.

Other two valves would be just Autos.

Nothing will work if there isn't enough head from the header tank. Wondering if that could be raised a foot or so, being careful with the lagging afterwards.

Apologies up front and please just ignore me if there is something I'm not understanding in all this.

Have a good BH.

Cheers,

Roy

 

[Old man Jim]

T off up then down to the valve, and keep the vent valve above the main pipe (manual valve) is what I'm imagining. Perhaps I'm not visualising something right. Valve would be upside down (for the collection tun). Might well be a better neater way.
[automerge]1590393834[/automerge]

Or better still:

(Only one of these) T off the pipe where the air collects the worst, go up, elbow to left or right to get off the line of the pipe, then into T to go up to an auto vent valve, and down to a manual vent valve placed over a tun dish (funnel) with waste to outside (ideally visible flow outside). The manual valve is just to be cracked open for filling the system. All that has to be lower than the header tank.

Other two valves would be just Autos.

Nothing will work if there isn't enough head from the header tank. Wondering if that could be raised a foot or so, being careful with the lagging afterwards.

Apologies up front and please just ignore me if there is something I'm not understanding in all this.

Have a good BH.

Cheers,

Roy

Thanks again Roy, the header tank and main tank are already elevated on a purpose made "table" approx a metre above the ceiling joists ...and the bungalow roof is a low pitch so can't take it up anymore.
I like the idea of breaking into the pipe with the air ....not fussed on a tundish set up though .

 

[Old man Jim]

Just discovered you can still buy replacement new glands with pin for the Danfoss TRVs .......and they say they can be replaced without draining down

 

[ShaunCorbs]

Just discovered you can still buy replacement new glands with pin for the Danfoss TRVs ...and they say they can be replaced without draining down

yes you can but need the special tool to do it (without draining down)

 

[Ric2013]

* And to be honest , I'm not a big fan of Combi boilers.

Please do not confuse a combi(nation) boiler with a condensing boiler. While (nearly) all new boilers are condensing, i.e. highly efficient, not all new boilers are combis. A combi boiler produces hot water instantly on demand - but you don't have to choose a combi model if you prefer stored hot water!

 

[Old man Jim]

Just wanted to update you and say thanks to everyone for their help :
Solved the problem of the sticking pins ....I bought replacement Danfoss Glands that incorporate pins ....and are easily changed without draining down ...no special tools required , just a spanner .....incredibly easy and works a treat !
I also changed the manual air valves in the loft to automatic air valves ......time will tell if they prove successful .
Thanks again for all your assistance Guys , much appreciated.