Why do some installers not use auto fill valves?

FranklinD · November 2014

A good friend of mine recently had a new boiler (natural gas) installed in his house. 1912 house, gravity hot water system, now has a pump. The install looked good to me, but he called the other night with a question (he lives 120 miles South of me).

He was going to bleed radiators as the install was just finished a week or two ago and he was thinking he might have a few air pockets around. He had a question about adding water to the system to bring the pressure back up. He sent a picture, and I noticed that he had NO pressure reducing valve/auto fill, just a backflow preventer and a ball valve.

He has the same setup as me basically. A Honeywell air separator, with a vent on top of it, is plumbed into the supply line out of the boiler. There is a line from the bottom of the separator to the expansion tank (bladder type) on the floor, and the cold fill line is tee'd into that line. So if I'm right, this is 'air removal' versus an 'air control' type system.

Why would they not install an auto feeder/reducing valve? He had a very reputable company do the work, and everything else they did really does look good (except, again, the pump on the return, as always).

My thoughts were that on an air removal system, you kind of need to have that auto feeder...but maybe not. I'm just so used to seeing them on every boiler I've ever looked at (whether it had a bladder type tank or a ceiling mounted compression tank) that I was shocked to not see this inexpensive part on his VERY expensive installation.

Thoughts?

Gordy · November 2014

Some believe....... I guess they will get the service call for gurgling system, or no heat, and they know to watch the pressure gauge when they add water to top off the system. They probably don't believe the homeowner may give it a try, and the system is tight as a drum. Hope they installed a LWCO.

icesailor · November 2014

The installer must be a very young person. Myself, now retired and old, always filled heating systems from the top down, depending on the fill valve to maintain the needed pressure on the upper floors, while on fast fill. Once the upper floor was filled, I could run down to the boiler and close the fast fill. Then, the PRV could then keep filling and I could keep venting. No multiple trips up and down multiple flights of stairs. I'm getting tired just thinking about all those stairs to climb with a large cup and a venting device.

Then I remember, they're smart and I'm not. The thought of filling heating systems alone without a PRV is just mind numbing.

Then, there's those senior distracted moments when I forgot to shut off the fast fill lever. I was done, picking up my tools and KERPOOOOSH!!! The relief valve opens at 30#. And just a 1/2"all valve to fill a system?

Robert O'Connor_12 · November 2014

Many open systems didn't use pressure reducing valves. You filled using altitude gage. Maybe installer left what was already there..(just a guess), meaning, possibly the part of the piping that wasn't touched during install.
As far as the pump location goes, I prefer it on the return in a converted gravity system. I'd bump the pressure up slightly just under spring pressure of relief valve & bleed away.

FranklinD · November 2014

Gordy, I believe it's a Buderus GA124/23. There was no LWCO listed on the invoice, and I'm not sure if that boiler has one included in it. It's an option card for my Burnham. I do know that he does NOT have the Logamatic (?) control panel on it.

Ice, that's what I was wondering...in a two story house, basement boiler, bleeding top floor radiators, I'd think that'd be a HUGE pain in the arse, running back and forth. I myself have my auto fill set at 12 psi and the ball valve upstream open just a crack. Seems like every time I think about closing it for good, I hear the auto vent burp a tiny bit of air out and that changes my mind for awhile.

Glad I'm not alone in my thinking then. All I know about the actual installer is that the company he works for refers to him as their 'master pipefitter'. Which seems like an odd title, given the huge amount of copper ProPress fittings he used. I understand they're faster and all that, but with all the plumbing they had to do to connect his 2 pairs of mains and everything else, it looks kind of like a lumpy copper mess to me. Don't get me wrong, I know nobody pipes hot water systems in steel/iron anymore, but my new boiler was all done in 1-1/4" copper with soldered joints. Cleaner look in my humble opinion.

Gordy · November 2014

Ice remember the young ones don't go it alone. A guy in the basement, and one upstairs talking on cell phones saves a lot of foot steps.

icesailor · November 2014

FranklinD said:
Gordy, I believe it's a Buderus GA124/23. There was no LWCO listed on the invoice, and I'm not sure if that boiler has one included in it. It's an option card for my Burnham. I do know that he does NOT have the Logamatic (?) control panel on it.

Ice, that's what I was wondering...in a two story house, basement boiler, bleeding top floor radiators, I'd think that'd be a HUGE pain in the arse, running back and forth. I myself have my auto fill set at 12 psi and the ball valve upstream open just a crack. Seems like every time I think about closing it for good, I hear the auto vent burp a tiny bit of air out and that changes my mind for awhile.

Glad I'm not alone in my thinking then. All I know about the actual installer is that the company he works for refers to him as their 'master pipefitter'. Which seems like an odd title, given the huge amount of copper ProPress fittings he used. I understand they're faster and all that, but with all the plumbing they had to do to connect his 2 pairs of mains and everything else, it looks kind of like a lumpy copper mess to me. Don't get me wrong, I know nobody pipes hot water systems in steel/iron anymore, but my new boiler was all done in 1-1/4" copper with soldered joints. Cleaner look in my humble opinion.

I'm a Master Pipefitter and have a license to prove it. Issued by the Department of Public Safety in the Commonwealth of Massachusetts.

icesailor · November 2014

@Franklin

Ice, that's what I was wondering...in a two story house, basement boiler, bleeding top floor radiators, I'd think that'd be a HUGE pain in the arse, running back and forth. I myself have my auto fill set at 12 psi and the ball valve upstream open just a crack. Seems like every time I think about closing it for good, I hear the auto vent burp a tiny bit of air out and that changes my mind for awhile.

Its far easier to just start filling and flip the fast fill lever. Run to the top floor and start venting. The water only goes up the venting pipes. The radiators below will give you a big air cushion against over pressure. . Then, go down to the lower level. The vacuum in the radiators and piping hold the water in place because there is no air in the mains. When you notice the lower air pressure getting quite high, go run down and turn off the fast fill lever. Then, with the higher pressure above, the lower floors vent rapidly. I also turn the burner on because the boiler is filled with water. If the circulators start, you can feel warm water entering the radiators.

If it is series looped baseboard, I just purge it at the boiler. When the water comes back warm then hot, its done. If it is drained and no proper way to purge it, I fix it, then fill it. Or, at least I did.

What took me less than an hour, probably takes someone else a few hours just venting and purging.

FranklinD · November 2014

Rob: I did ask him that, and he said it was all new piping from the cold supply near the water heater, all the way over to the boiler. New ball valve and new backflow preventer with a vent pipe down to the floor.

I actually have the pump on the return on my converted gravity system. The system is relatively small, the flow is pretty slow, and I haven't noticed any sort of issues. That's where it was on the old boiler too. It just happened to be where the installer put it (old habits and all). I have some repiping to do come spring, for a boiler bypass and an indirect HWH I'm adding, so we'll see what gets changed then.

I appreciate all of your insights on this topic, folks. He is located in St. Paul, MN, so I'm not sure what the requirements for such things are there. It just seemed odd to me to leave out such an inexpensive part. And my friend certainly would've had an experience had he turned the valve wide open and gone up to bleed the radiators. He has no floor drain in his basement. But that's another story.

He's an IT director of some ilk for a huge health care conglomerate there, and this stuff is a little beyond him...at least he loves the cast iron radiators and didn't rip them out in favor of forced air heat during his renovations.

Thanks again!

unclejohn · November 2014

Ice;
If you vent the top floor first what keeps the water from falling down when you bleed the lower floors? I bleed low floor first and work up. By the way that boiler does have a low water cut off built in.

SWEI · November 2014

We always install isolation/drain valves on the boiler(s) and expansion tank. Filling and purging systems is a piece of cake with 60-100 PSI of water. Throw in a 24 hour hydrostatic test while you're at it.

icesailor · November 2014

Gordy said:
Ice remember the young ones don't go it alone. A guy in the basement, and one upstairs talking on cell phones saves a lot of foot steps.

Not so. The guy in the Cellar is waiting for the call to stop the fast fill. The guy on the third floor, venting the radiators, has opened the air vent on the 4 radiators at the same time. They are both talking on their cell phone or texting. The guy on the third floor doesn't hear the water coming out the radiator in the other room. The guy in the cellar gets off the phone or stops texting, and hears water coming through the ceiling to the second floor. He yells up to the guy on the third floor who can't hear because he is using his good ear on the phone. The old guy in the cellar (not me) has to run up to the third floor to find the leak. By this time, three radiators are spewing water on the floor. The one that "Phone Man" is standing next to has the air vent painted shut by quality painters who ALWAYS paint the coin vents shut so they match the radiators.

icesailor · November 2014

unclejohn said:
Ice;
If you vent the top floor first what keeps the water from falling down when you bleed the lower floors? I bleed low floor first and work up. By the way that boiler does have a low water cut off built in.

Its my experience that the fast fill or slow fill will pressurize the air in a radiator or the riser pipes. If you fill the system, its set for say 12#, and you start at the bottom, the upper radiators act as mini expansion tanks. They will push the water back down the riser pipes and add water pressure to the filling. If you fill from the bottom, then go to the top, when you first vent a radiator, there is a heavy rush of air that is still compressed in the radiator and risers. As the pressure drops, it will go negative and the weight of the water, trying to equalize, will pull air into the system. Because the PRV is set at 12#, it slows filling to a trickle as the pressure approaches 12#. If you really needed 15# for adequate pressure on the upper floor, you can sit there all day holding the vent open and holding a cup to catch the water while sitting there waiting on a top floor. When the sound of air rushing out of the vent stops, and you're waiting, spit on your finger and put it on the vent hole. If the spit sucks in to the vent, the pressure is negative. If it bubbles, it is positive.

If you fast fill the system to 25# when you start, and turn off the fast fill, you can go to the top floor and start venting with a vengeance. Then go down a floor. The boiler and mains will all be filled. They have to be because you had enough pressure to get to the top floor. The water won't run out of the radiators or the risers. Just like the childhood experiment of holding a inverted glass full of air over a pot of water. The air can't get out. Then, put the glass in the water invert it so the opening is down, and as long as you don't break the surface, the water in the glass won't fall out. Like the water'er I use for our cats

You go to the lower floor and vent away. The air pressure is always higher and the 12# is more than sufficient to vent the air. I always start the boiler so that it starts heating and pumping as soon as possible. I can feel the hot water entering the radiator.

Its part of the way I understood why you often need higher system pressures in hot water systems. To have enough venting pressure on upper floors. Put automatic coin vents on radiators on a second floor, leave the boiler set at 12#, and watch the air go in. They vent both ways. High pressure expels the air, low pressure sucks it in.

IMO

I never have to go back and re-vent radiators. Or baseboard for that matter.

Why do some installers not use auto fill valves?

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