Air management / Elimination

Hilly

Customer complains he has to bleed often - every few days. He has lived with hot water growing but this is a new (old) home to him. He assures here is air coming when he bleeds and it's not just water. Here is near boiler piping. This is fairly typical around here for the most part. My question is... How or what would you propose to re-pipe near the boiler to ensure air isn't a problem. I know air Sep, bladder tank and pump away. Or can you keep a line scoop and still utilize the steel tank. Would just moving the pump be a solution. It is a friend's neighbour and I'll take a visit this weekend but I'd like to get a few ideas before I get in there.
TIA

HVACNUT

I assume he has to bleed the rads as there is not a purge station at the boiler.
First, with the steel x tank, it's an air control system, so there shouldn't be any automatic air eliminator like the one on the supply riser. Tighten the cap on that auto vent.
If the system is new, it might take a lot of bleeding to get all the air out.
Where is the auto feed valve? Is there pressure on the boiler?
Are any heat pipes running through a slab, possibly leaking?
You could repipe using "pumping away" and make it an air elimination system using a diaphragm tank. It should have been done with the installation.

Ironman

What's the cold static fill pressure and how high is the highest emitter above the boiler? What type of rad's, CI or BB?

Hilly

1. Make-up Water is tee'd into the typically labelled "drain port"
2. Pressure is 12psi
3. It is a mono-flow system with all the piping exposed in the undeveloped basement. so there is no leak
4. It's a 2 story house. 7ft basement, 8ft main, then the 2 heaters on the top floor... meaning about 15' is the highest emitter.
5. These are "old-school" fin-tube cabinet style heaters.

I mean sure it means making more work for me if I pipe it pumping away, but if I can make them happy then more economically then I can have a customer for life I'm sure. Granted I don't think it'd take long to convert to pumping away and setup a purge too. I know that is 100% successful but I see so many system similar to this that just seem to work too.

Boon

Can't tell from the photo if the terminal block on the pump has been turned or if the pump is pulling water through the return.

Ironman

Boon said:

Can't tell from the photo if the terminal block on the pump has been turned or if the pump is pulling water through the return.

The 3rd pic shows its pumping down into the boiler.

Ironman

Hilly said:

1. Make-up Water is tee'd into the typically labelled "drain port"
2. Pressure is 12psi
3. It is a mono-flow system with all the piping exposed in the undeveloped basement. so there is no leak
4. It's a 2 story house. 7ft basement, 8ft main, then the 2 heaters on the top floor... meaning about 15' is the highest emitter.
5. These are "old-school" fin-tube cabinet style heaters.

I mean sure it means making more work for me if I pipe it pumping away, but if I can make them happy then more economically then I can have a customer for life I'm sure. Granted I don't think it'd take long to convert to pumping away and setup a purge too. I know that is 100% successful but I see so many system similar to this that just seem to work too.

Without going into a drawn out technical explanation as to why, would you try something simple first?

Close the bleed cap on the air vent and set the cold static fill pressure to 18 psi. Then, see how it does for a couple of weeks.

JUGHNE

Do you have a bleeder on each cabinet convector?

Hilly

I will absolutely be closing the bleeder and attempting to bleed each emitter first. I'm going to run by on Monday to have a look. I always forget that the air vents and steel tanks don't play well together.

hot_rod

I don't know how much $$ you want to spend to redo the system, i agree with Bobs advice, go for the low hanging fruit.

Something I have always wanted to try is putting a great air sep like the Caleffi Discal and run the vent port up to the tank. We have an adapter for the metric thread on those vents to convert to1/4 NPT to use a copper tube to discharge the vent port to a safe location.

Any other auto vents in the system would need to be sealed off, still, else you lose the air bubble over time.

The should give you high efficiency micro bubble removal and maintain the air space in the steel tank. Think of it as a high performance Airtrol ™ type system.

Keep in mind with bladder less tanks the water is always in contact with the air. In the down months the cooler water does re absorb some air, so the purge process needs to happen every time the water heats and displaces air. I think a micro bubble type would excel under those conditions.

Size of the tank is greatly reduced with a bladder or diaphragm tank, probably by 1/2 or more. Also, less heat loss in the room So a few other advantages to a air removal diaphragm type system.

leonz

HVACNUT said:

I assume he has to bleed the rads as there is not a purge station at the boiler.

First, with the steel x tank, it's an air control system, so there shouldn't be any automatic air eliminator like the one on the supply riser. Tighten the cap on that auto vent.

If the system is new, it might take a lot of bleeding to get all the air out.

Where is the auto feed valve? Is there pressure on the boiler?

Are any heat pipes running through a slab, possibly leaking?

You could repipe using "pumping away" and make it an air elimination system using a diaphragm tank. It should have been done with the installation.

==================================================================================================================================================================


Well his inherited problem is a big problem caused by a mistake in plumbing.

1. The steel expansion tank has no airtrol valve that that I can see.
2. There is an automatic air vent in the system!!!!, and no wonder its not working correctly as the air vent has disposed of the air cushion in the steel tank and let the steel expansion tank water log!!!!!!!!!!

He needs an airtrol valve for the steel expansion tank and he has to toss each one of the automatic air vents in the scrap bucket after you plug the tapping for each automatic air vent.

1. he needs to drain the system to install the airtrol valve in the steel expansion tank.
a. Use a lot of pipe strap to hold the tank up. I have 3 straps holding up my 15 gallon steel expansion tank. I would use four lengths of pipe strap on that steel expansion tank screwed into the floor joists on the outer side of the two floor joists used to hold it up now.
2 install a ball valve to shut the steel tank off from the system to hold the water in the tank.
3. remove the automatic air vents and plug the tappings so they do not leak.
4. with the system drained he can install isolation valves on the circulator at that time before he fills it.



After that he can fill the system back up and vent the air out of the radiators THEN shut the fill valve off and leave it off as he will open the valve to the steel expansion tank and after that is done he will drain the excess water out of the steel expansion tank and then close the drain valve on the airtrol valve.

Putting tags on the valves and an explanation sheet in a plastic sheet bag or small notebook shows that it was done properly and done well with information for the next person and hanging it by the boiler would be a good idea to make sure the next person does not screw it up.

Hilly

I have seen only 2 armtol tank fittings installed in my life.

leonz

The B+G AirTrol valve I have in my steel expansion tank works perfectly as it has no moving parts or a bladder that can fail.

In the airtrol valve casting it has two channels one for the hot water to rise into the steel expansion tank which then cools and and releases the micro bubbles into the air space.

They work well and always have because they are simple and have no moving parts. they stop working well when mistakes are made with the plumbing because the installed is completely unfamiliar with steel expansion tanks and how much better they work.

Its just like Dan says the steel expansion tank just sits there hung in the basement joists and and the airtrol valve does it job with no moving parts.
Mistakes are made with them when people do not know how they work and they are ripped out needlessly OR the installer installs automatic air vents in a new installation and they get no heat calls and they do not know what they did wrong.

I had one plumber tell me to the steel expansion tank had to be removed to solve my issues with a second defectlve hydrostat 3250 Plus on my dual fuel coal stoker boiler and I knew that was not the problem it is the fact that the keystoker folks continue to use the hydrolevel units when they are ment only for cold start oil and gas boilers rather than mechanical triple aquastats and mechanical/water contact LWCO sensors.

Hilly

The boiler fitted above has had a couple of issues for the owner. The cushion tank does water log and he drains. There's heat not getting to 2 heaters. It is a monflo and the heaters that don't work have tee's quite close together. He has been researching and would like to lose the monoflo and go with a homerun system. This to would be my preference too. He can't afford to do the whole boiler re-fit and homerun ATM. Would you feel comfortable doing a homerun system and leaving the boiler (micro bubbler, pump away, etc) piping to a later date.

Hilly

He was a relatively new owner here and winter has approached. So he's revealing a few things now as the temperatures dip.

leonz

I believe he also forgot to shut the fill valve off when he drained the steel expansion tank and left it shut off.

hot_rod

The tank will waterlog if there is a working air vent and an open fill valve. After time air in the tank is reabsorbed into the hot water and vented out, fill valve adds more water.

MonoFlos can be a bugger to purge.

If you are going to do any work I'd first lose the compression tank, add a good microbubbler, and diaphragm expansion tank connected to the suction of the pump. the circulator can stay on the return as long as the ex tank connection is there.

These would seem to be an easier first step compared to junking the monoflos and repiping everything. Plenty on monoflo systems working just fine once they are purged.

Hilly

@Hotrod I was thinking the same. Plus the makeup water is at the suction side too. Good easy spot for the expansion tank. There are 10 heaters and 4 of them have the tee's no more than 2" apart. Of course they are the ones not heating. And of course 2 of them are where the children sleep. According to the service sheet the bfp, prv and circ are new. So really it's just the expansion tank and AS needed. He decided before i got there to go ahead a redo it all and he was happy when I told him there were a number of things I could use and deduct from the costs for him.
Thanks for the input guys.