hot water bleeding

Junior_3

Hello everyone ,i was just wondering if there was book or seminar that will show or teach how to bleed different hot water systems.i work as a service tech (hvac and gas appliances)for a large gas utility company for about 3 years and most of the guys in just refer" wet work" out to plumbers(pumps,air bound systems,zone valves)and the guys that do do that work seem not to want show anyone anything.But to be a better tech i would like to learn it especially systems with filltrols and that arent valved off to help bleeding.thanks

Mike T., Swampeast MO

Air Removal

Of the many book I have on hydronics, there is little or nothing in them regarding how to fill and air-purge a system. Of course most of my books are rather old, so more modern texts may cover it better--I'm really not sure.

How easy or hard it is to fill and remove the air seems to have MUCH to do with how much the original system installer considered such in their design AND how much the system has been tinkered with over time.

Personally, I believe that for all but the simplest of systems, installers should leave instructions on how to fill/purge THIS system--unfortunately that doesn't seem to be common. Sure seems to me that this would remove a LOT of cussing from the world...

Since hydronic systems have almost infinite variety, you could fill pages and pages or even books and books on the topic and still not cover many situations--let alone be able to come up with a good index.

IMHO the seeming fact that "the guys that do do that work seem not to want show anyone anything" isn't because they're trying to hide something, it's because you mainly learn such by experience (and cussing), and teaching is nearly ineffective.

lchmb

Mike

I will agree that we all learn by doing....But can you imagion a company that send's a man into cellar's and say's go for it you'll learn??? I would wonder about a crew that wouldn't help each other out.

jim lockard

JR.

One place you might start is on the left hand side with Heating Q&A, from there travel down to Books and more. Dans books will help you understand both water and steam heat. As for the guy that saves the valves, a good wack with a 14" Ridgid would be too kind. Best Wishes J.Lockard

Rookie_3

Mark Eatherton1

Purging hot water heating systems...

Boy, is that a loaded question...

Lets start with the antiques and work our way to present day.

If you're dealing with the upright cast iron radiators, you set the fill valve to maintain 1/2 PSI per vertical foot of system elevation, and add 5 PSI. Then you start at the lowest radiators and work your way upward, MANUALLY bleeding the air from each radiator. Make sure the pump (if any ) is OFF, otherwise, you could be chasing your tail AND the air. Carry a towel with you because you generally spill just a little bit of fluid at each radiator.

If you're dealing with a one pipe monoflow or any other type of flow directing T type of system, the same basic rules apply, except that you want to make sure that the convector has its bleed point at a high spot to trap the air. Again, start from the bottom and work your way outward and upward.

In the case of a two pipe direct return, or parallel return system, it gets a bit more complicated. On the systems I design and install, I design "ease of purging" into each system. Not all installers do or did. Sometimes, it requires you to think backwards. In any case, you have to think like water. I generally set my systems up so that I can power purge. That is, I use the available water pressure to force the water in, and force the bubbles out. I also recommend that the outlet hose be dropped into a 5 gallon bucket placed strategically over the floor drain serving the boiler. This way, you can see when the zone is purged, because there will be NO bubbles coming up from the end of the hose. Start with those zones that are lowest, and closest to the heat source, and work your way outward. When done with that floor, go to the next floor up, and again starting with those zones closest to the boiler, work your way outward. Continue doing this until all circuits are purged.

In the case of radiant floors, the methodology is the same as for closest first and working outward, except that if you have more than two tube circuits on a manifold, it is advisable to close all but 2 circuits at a time. This allows adequate water pressure to quickly clear the tubing of bubbles. In most all cases, you never want to leave the pressure reducing bypass wide open without constant supervision. Thats tough to do when you're the only body on the job site. Often times, it helps to keep one person in the mechanical room, keeping the pressure boosted, while the other body moves through the system opening and closing valves. Radio contact helps IMMENSELY.

Once you think you are done, open all the necssary valves and allow the pump (if there is one) to do its thing. You can tell if the system is working correctly by quickly closing the valve nearest the pump. If water is flowing (check one zone at a time) you will hear an audible WHOOsshh as you quickly close the valve.

Another method of flow confirmation is to feel the pipes. The return should start out cold on a zone that hasn't been opened in a long while, and will get warm as the pump moves water back to the heat source. You SHOULD hear what sounds like marbles rolling through the pipes. These are smaller air bubbles working their way to the air elimination system. The system should be virtually silent within a week.

Hope I've not forgotten anything, and I hope you take what you've learned here and pay if forward.

Good luck in your ventures.

ME

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Mike T., Swampeast MO

Back to Antiques

If the old plain compression tank is still being used, look for an "Air-Trol" fitting. The tank will usually be hanging between joists near the boiler. The Air-Trol generally has a red painted body and connects to the bottom of the tank. There will be one pipe connected to the side of the fitting (that's the connection to the system) and there's a little brass drain fitting at the bottom.

If you find this fitting, the filling procedure is different. First, ensure that the tank is empty--there's usually a drain fitting at one end. Then close ALL air vents in the system.

Then open ONLY the bleed valve on the Air-Trol. Put a bucket underneath as there's going to be quite a bit of spitting. Begin filling and continue until a good, clear stream of water ONLY comes from the fitting. Then close that bleeder and begin bleeding air from the rest of the system. Then either return in a couple of weeks or tell the customer to bleed air from all the rads.

If you find that you accidentially left some other bleed valve open, it really is best to re-drain and start from scratch--otherwise you (or the customer) will be "chasing air" for quite a while.

If you regularly work with old standing iron systems, make quite a number of these. Soup cans are great because they don't have a bottom seam to rust and leak and those can openers to work by opening the top seam make for a nice, safe edge that doesn't have to be filed.

jim lockard

seminar

Print Marks post out Jr. Mark said it all good job. Best Wishes J.Lockard