Need help draining and refilling water heater/hydronic heating system

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Old 12-09-13, 04:17 AM
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Need help draining and refilling water heater/hydronic heating system

This year I went to start my water heater for the radiant heat system in my basement and the heater works fine, but won't circulate. I checked the pump and it works but doesn't move water. I replaced the Bell & Gossett automatic air vent 97 due to the cap breaking with a Watts 0590715 Vent. When turned on..nothing moves. In the past you used to be able to bleed some air out with the vent. Not now. When opening the system up at the pump has a very interesting smell almost like old fuel. I am guessing that there is air preventing the pump from moving water. Any help on a remedy would be great for a system with a hot water heater.
 
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Old 12-09-13, 05:32 PM
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What is the pressure and temperature reading on the boiler gauge?

Can you take pictures and show us the system you are working on?
 
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Old 12-09-13, 07:51 PM
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Here are some pics of the hot water heater system.Name:  IMG_7208.jpg
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Old 12-09-13, 08:48 PM
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I'm not going to go into how I'm not a fan of using water heaters for heating systems... ooops, I guess I just did... but be that as it may:

I don't see a pressure gauge in the pics, only temp...

I'm wondering if there is any pressure in the system at all.

On the top of the FILL-TROL tank there is a 'schrader' (tire) valve.

What pressure do you read when you put a tire gauge on that fitting? I'm betting you will read ZERO.

Is the red valve below the tank OPEN?

I don't have a clue as to what pressure your system was designed to operate at, but if it's all radiant floor, I'm going to presume that it should be at LEAST 12 PSI.

If you have ZERO pressure in that tank, you will have zero pressure in the system as well.

Theoretically, once pressurized, you should not lose pressure... and losing pressure might indicate the dreaded "L" word... where else would the pressure be going?

Anyway... If you have a pump or a compressor, try adding an air charge to that Fill Trol tank. As you add air, you should hear water start to enter the system. You may hear air coming out the air vent as the water enters and pushes out the air. Bring the tank up to 15 PSI and see what happens.
 
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Old 12-10-13, 09:38 AM
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Domestic hot-water heaters' warranty is void if they are used for hydronic space heating. And, unlike hot-water boilers, they are not approved with an ASME "H" stamp in accordance with the boiler & pressure vessel code, so they don't have the design and safety margins of a boiler. The usual failure mode of water heaters, with glass-lined tanks, is they spring a leak, which is not good.

Water heaters are typically provided with a T&P relief valve, which may be too high a pressure setpoint to protect a hot-water heating system. The original relief valve can be replaced with a conventional 30-psi valve used for boilers, but then there is no backup protection against overheating in the event of a failure of the thermostat on the water heater. This, in my opinion, is unsafe.

Water heaters are cheap, though.
 
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Old 12-12-13, 05:10 AM
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No pressure. Sorry what's the dreaded L word?
 

Last edited by ilaudio; 12-12-13 at 06:05 AM.
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Old 12-12-13, 07:03 AM
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No pressure. Sorry what's the dreaded L word?
The red valve, open? or not? Needs to be open.

Try adding the air to the tank. This will allow water to feed into the system. You should hear it feeding after you add the air to the tank... unless the tank is 'shot', in which case you have to replace the tank with a SPECIAL type of expansion tank. That is a FILL-TROL tank and they are NOT the same as the ones off the shelf at HD or Lowes.

The "L" word... LEAK
 
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Old 12-17-13, 05:40 PM
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Thanks for the help. Just needed to add air to it. Works now.
 
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