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air in hot water supply

Newbie here and I looked but didn't see relevant threads and apologize if this is the wrong area or a repeat. Anyhoo... I submitted the question to ATOH but thought I would post it here also in case they pass on my submission. Why settle for one rejection when you can go for two.?. :p

My new addition has a boiler and dual purpose tank (radiant and potable). A well supply line is split to supply the old copper and the new pex. Pex feeds the appliances via home runs from a manifold. Problem: excessive air emanates from the hot side in all faucets and spigots but not the cold side. Water dispensed from the hot side into a glass looks like Alka Seltzer water. Inactivity will also cause large air pockets and faucets will 'burp' when turned on after a week of non-use. Also, I do not have the same issue in the old house with the copper and a dedicated hot water tank. The plumber who installed it says air is normal and doesn't know what to do. Is it normal or should I be looking for a new plumber?

Re: air in hot water supply

my tank had a spigot at the bottom, i attached a hose to the tank and let it run several minutes, this seemed to help.

Re: air in hot water supply

I will check my tank but I seem to remember all the plumbing running out through the top. Thanks.

Re: air in hot water supply


Could you post the brand name & model number of the boiler---this sounds like a combi boiler like the Biasi or Valiant units that have a diaphragm inside for the domestic hot water---they often act up due to mineral deposit clogging.

Do you have well water???---if so, are you sure your well pipe connections to the hw are not picking up air from a hole or tear in the well pump???

Re: air in hot water supply

The boiler is a Buderus brand and I think the tank is also. I'll have to check because I did not pay much attention to it. The system is less than a year old so I doubt that is enough time for mineral deposits to form though I know my well water is a bit hard. If the air was coming in at the well, I would expect to see air at all fixtures of the old house and new and on both cold and hot sides. As it is, the air is only present in the new fixtures and only from the hot side. I'll verify make and model when I get a chance tonight.

Moon Over My Hammy
Re: air in hot water supply

I don't know what a dual purpose tank is. I can't imagine mixing heating water with drinking water.:confused:

I do know my water tank has a label that says heated water releases hydrogen gas and if not used for a week or more to turn off and take precautions when first opening faucets having no open flames in the room. We have to have an expansion tank to take up the pressure of the expanding heated water and if there is a lot of hydrogen if the tank is set too high temperature and not used the faucets when first opened can spurt and burp, which is why setting to pilot only or vacation mode important if being away from the house for a week or more.

When I complained about the water to the city they called the bubble-milky disturbance "turbidity" and if left alone a glass of water settled down and became clear after a while. They did an extra water test on samples from my home and they came back within normal limits. They explained that heated water tends to concentrate the minerals and salts. We were advised to follow the directions from the tank which said to drain sediment every month for hard water or every three months for soft water. Since we have harder calcium water its my job to do it every month.:(

A plumber should know more about what is going on get a new one who knows more about indirect tanks and designing boiler systems and or a boiler specialist maybe.

Re: air in hot water supply

'Dual purpose tank' is just my name for the system and may not be entirely accurate. I'm pretty sure they have a technical term for the system but it escapes me at this point. Anyhoo...radiant and potable water does not (should not) mix in the tank. Best I understand, the tank is pretty much a hot water tank with a tubing coil that is connected to the closed loop for the radiant system. The boiler heats the water for the potable system which in turn heats the coil(s) that supply heat (and only heat) for the radiant system. For me, the boiler is a Buderus Logamax plus GB142 and the tank is a Logalux S-120. I did notice a fitting on the lower section of the tank but it doesn't appear to be of the 'usual' spigot with garden hose threading. Since it is a potable tank, I'm pretty sure this is the drain for sediment and what not. I will flush it to see if that helps my air issue any.

However, the placement of the fitting makes me think that it is for the evacuation of sediment and not gas/air as they are lighter than water and would invariably amass at the top of the tank, where the supply outlets also happen to be. When you bleed air from a system, it is usually best to do so at the highest point, not the lowest.

Moon-ie: what company manufacturers your tank? I'm curious because they sound like they might also market that water injection system for cars that claims to increase mileage. As the car talk guys say: booooogus. The temperature at which the molecular bonds of H20 would break down to create separate hydrogen and oxygen gasses is way higher that what is available on your temperature setting dial else we would be running hydrogen vehicles because there would be filling stations on every corner of the street. That is not to say your experience is utter nonsense as I've seen cases wherein people were able to light the gaseous emissions coming out of their faucet. Those are anomalies, however, and if that warning were mandated for all hot water tanks produced, one would think that all tea kettles would also have to include such a disclaimer. As it is, attempting to light the steam from my tea kettle only singes my hand and dampens the lighter though lighting farts is another story. :rolleyes:

As for the plumber, I really liked him and recommended him until this point. He was really knowledgeable an patient with the scheduling and took the time to explain what he was doing and how the parts worked. However, I noticed recently a change in demeanor as he showed more frustration while working and an adversarial bend that I had not noticed before. When he sent me the bill (instead of the gc) I asked him the status of the air in the line issue and it was suggested 1) this is normal (though the cold line and the old hot water tank does not exhibit this behavior) and 2) I should google the problem if it bothers me. His tone became more adversarial when I pressed the issue and he retorted by asking me if that meant I intended to withhold payment of the bill. I'd already told him that I would take care of him should the gc balked but I do think I paid $75/hr. for a 'professional' which implies that person should have an understanding of the products they are using and installing and remedy any issues involving said products. As it is, the more 'problems' I have to solve myself, the less I'll need his services.

Sorry for the long post/rant but the issue is still fresh on my nerves. Thanks for the 'ear' and all the input thus far. :)

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