Hot water heating question

[kerry]

Friend has a hot water baseboard heating system. Needs new zone valves. I told him I would help him. He says he knows of no air bleed fittings in the system. Does anyone know how a system like this is emptied and filled if it has no provision for bleeding air out of the system?

[spdrun]

I think none is needed -- there are no radiators with space for air to "hide." It's series of straight pipe lengths, water is pumped in by the circ pump under pressure, and it's pushed to the expansion tank, which does have an air relief nipple. SOME systems do have bleed valves under the metal covers that are operated with a square key.

[David Wilson]

I have a hot water baseboard system with 2 zone valves. One for heat, one for domestic hot water. I have a bleed valve. I don't know of any system that does not have a bleed valve. That air has to go out, somehow.

[lorainfurniture]

At the end of the baseboard there should be a bleeder. I don't believe any system can be filled without a bleeder of some sort.

[razvy]

Not every baseboard needs a bleeder , but at least one per zone , usually on the highest point works the best .

[rscurtis]

When I had a NG boiler installed in my house on LI, the circulators were placed on the "hot" side of the system so they always had a supply of air-free water from the boiler. Any returned air went to a riser on the boiler where it was removed with an automatic bleeder. If the circulators are on the more normal "cold" side, as soon as a slug of air hits them, they stop pumping- in that case, you'll need bleeders, or have to purge the air by flushing the baseboard with the feed water supply.

[Honus]

The system has to have an air vent somewhere. I'll bet there's something where ever the expansion tank is. I have a radiant floor system served by an instantaneous hot water heater. The heater, pump, expansion tank, and other such gizmos are in a downstairs room at the low point of the system. The system has one bleeder and it is downstairs. Works fine. As spdrun says, if the system doesn't have any sharp, local high points like you would have with old-fashioned radiators, one bleeder at the expansion tank fitting should be enough.

[Brian Carlton]

Originally Posted by kerry

Friend has a hot water baseboard heating system. Needs new zone valves. I told him I would help him. He says he knows of no air bleed fittings in the system. Does anyone know how a system like this is emptied and filled if it has no provision for bleeding air out of the system?

Your friend is correct

Baseboard systems are bled at the furnace. They have no traditional bleed valves.

If properly designed, the feed water regulation valve (which normally limits the pressure to 12 psi) has a bypass arm that allows unlimited pressure to the system. This must be used carefully and with the full understanding that you cannot exceed 30 psi without blowing the pressure relief valve.

The return line to the circulator will have a shutoff valve to prevent flow into the furnace.

Directly above the shutoff valve will be another shutoff valve with a spigot to allow a connection to a garden hose.

The system is bled as follows:

1) Ensure the valve for the zone you want to bleed is open. Manually move the arm on the side of the zone valve to lock it in the open position. (Do not turn up the thermostat).

2) Connect a garden hose to the spigot and run it outside.

3) Shutoff the valve directly above the circulator (and below the valve at the spigot)

3) Slide the bypass arm on the pressure regulating valve to allow unlimited pressure to the furnace.

4) WATCH THE PRESSURE GAUGE while keeping one hand on the valve handle at the spigot.

5) Open the valve at the spigot and keep the pressure between 20-25 lb.

6) "Shock" the system many times by quickly closing and fully opening the valve. The pressure will climb toward 30 psi and then fall (when the valve is fully opened) during the process..............not a problem............keep it between 17 and 27 psi.............don't approach 30 psi.

7) You can hear the air in the lines and, when the bleeding is complete, the noise from the air will stop (typically about five minutes).

8) Slide the bypass arm back to the fully regulated position.

9) Wait for the pressure to fall back to 12 psi and close the valve at the spigot.

10) Open the valve directly above the circulator.

11) Move the locking arm on the zone valve back to the normal operating position.

12) Repeat the above for each zone in the house.

[Brian Carlton]

Originally Posted by kerry

Needs new zone valves.

Many times the motors fail. There is nothing wrong with the valve itself.

If the name on the side is "Honeywell", you buy a replacement motor on e-bay and change it in about 10 minutes.

Not having to break into the system and sweat new zone valves: PRICELESS

[kerry]

Thanks. I wish. Existing valves are White Rodgers. I'm thinking of relocating the valves to a more convenient place and using a manifold/Pex/shark fittings to tie into the boiler pipes. Boiler's in a hole in a crawl space. Bad location.

[t walgamuth]

Is Pex rated for that use?

[kerry]

Pretty sure I've seen it done on This Old House.

[t walgamuth]

I'd say that is equal to seeing it on the internet!

[kerry]

Need to use oxy-barrier pex.

[Brian Carlton]

Originally Posted by kerry

Thanks. I wish. Existing valves are White Rodgers. I'm thinking of relocating the valves to a more convenient place and using a manifold/Pex/shark fittings to tie into the boiler pipes. Boiler's in a hole in a crawl space. Bad location.

I would replace the White Rodgers with Honeywell. You friend will thank you in the future.

Also, if you're going with Pex, you can buy the Honeywell valves with NPT female fittings and not have to sweat anything.