Heat Working Upstairs, Not Downstairs

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Old 02-17-14, 05:02 PM
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Heat Working Upstairs, Not Downstairs

New to the forum, hoping to find some help with my issue.

I have a rental property with a one zone boiler system that has been problematic in the past, but was working fine up until a few weeks ago when I had to replace the water heater.

I have bled the system numerous times, but the same problem keeps happening. The 2nd floor is heating normally, but the 1st floor is not heating as it should. When the tenant gets up in the morning, the temperature on the 1st floor is 10-15 degrees colder than it is set (depending on how cold it is outside).

All of the pipes on the baseboards are all hot, and I have bled every single valve along the pipes. I do occasionally get a few air bubbles, but after bleeding for several seconds, it goes back to just water.

When the heat is not working, the baseboards on the first floor are still radiating heat, just not enough to warm to the temperature that the thermostat is set at.

There is a bleeder valve on top of the boiler itself that I've noticed has air get trapped in it. When I would go up to look on it, I would bleed that air and the downstairs would begin heating (would still take about an hour to reach the set temperature).

I also received a message from the tenant tonight that said that this morning the thermostat had dropped itself to be set at 62 overnight (they usually keep it at 68-69)

The pressure and temperature are reading as normal anytime I go up to check. The circulating pump and expansion tank were just replaced about 9 months ago.

I'd like to fix this myself without having to go through a professional, but it's getting to the point where I'm going to have to call one in for my tenant's and my own sanity.

Should I just keep bleeding looking to see if there is another air pocket somewhere in the system, or are there other issues that I should be looking for?
 
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Old 02-17-14, 05:05 PM
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How big is the area? And where is the thermostat? I am no expert but I read several hundred posts on here and some have the same issue it seems like you might need to onstall a second zone to get a more even temp.
 
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Old 02-17-14, 05:09 PM
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It is a duplex, and the boiler is only heating one half of the house (other side has a furnace). So, it is only heating 2 radiators in the basement, half of a 1st floor, and half of 2nd floor. There is a finished attic, but no heat going to it.

The thermostat is located on the 1st floor (the floor that is having the problems)

As I said, it was working fine until the day after the new water heater was installed. In the past, I was having the opposite problem, the 1st floor was working fine, but the 2nd wasn't heating. That was solved by replacing pump and expansion tank.
 
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Old 02-17-14, 05:29 PM
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SD,
What did you shut off when you installed the heater that has to do with the heating system.
What type of system do you have. Two floors, is it monoflo, are you bleeding each individual rad.
That cap on that bleeder on top of the boiler should be left loose for automatic venting.
What do you call normal pressure. When your bleeding, are you building pressure first or are you just letting it feed to replace what you took out and just replacing the air.
 
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Old 02-17-14, 05:44 PM
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Spott:
Please forgive my ignorance on a lot of this. I will do my best to answer your questions, but I am still very inexperienced with dealing with boilers and such.
I had the water heater installed by a professional, but I observed so I could learn. The main water line was opened which he said could cause air to get in the lines and cause issues.

After doing some quick research, it is monoflow. You say the cap on the bleeder valve should be let loose, but it constantly squirts hot water as soon as the air is released if it is loosened. Am I just loosening it too much?

Normal pressure is around 20 psi when hot. I've tried to bleed it both ways. Usually I'll bleed without raising the pressure, then try again after I build pressure up to around 25 psi.

While talking more with my tenant, he told me that there is still a river flowing sound in the pipes in the basement, so there is still air in there. I plan on going up tomorrow and purging the system to see if that works. Unless anyone has any other ideas.
 
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Old 02-17-14, 05:45 PM
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Do you have a battery-powered thermostat? If yes, have you changed the batteries? I suspect the problem arising after the water heater replacement is coincidental.
 
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Old 02-17-14, 05:48 PM
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Furd, I will check on that tomorrow. Thank you for the heads up.
 
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Old 02-17-14, 06:11 PM
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SD,
The vent on the boiler should release air and stop when its done. If it's squirting water it is defective ans should be replaced. Close it until you do.
Having a stand alone water heater installed should not have effected the heating system unless he had to drain water from it. If he suspected air problems he should have shut the cold water feed off to the boiler.
The two systems should be divorced from each other.

If you can hear water then you have air and monoflo can be very difficult to bleed.
You cannot bleed it from the basement return line if you have been. Each rad has to be bled individually.

Get your pressure up to about 28 or just below relief valve limit which is 30lbs. Start fairest away with the ones that aren't working and keep pressure built up.
When you're done bleeding, drain excess water until you get to about 18psi. Start boiler and test.

with 1 t-stat and 2 floors it's going to be hard to balance anyway but it should reach whatever the temp is set for.
This is just to make sure the rads heat, but as Furd said if the t-stat is acting funny that's another problem.

Good Luck,
 
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Old 02-17-14, 06:22 PM
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Thanks Spott.

He did have to drain a lot of water when he replaced it. I do not recall him shutting off any cold water feed.

I will check the thermostat and continue to bleed. I have been just bleeding each radiator individually but upon doing more research, thought about trying to bleed from basement return line. Thank you for letting me know that it will not work for my system, saved me time and another letdown.

I guess I just haven't gotten it all out. There is a bleeder on the 2nd floor that has given me issues in the past. The annoying part is that when the lines were installed, they did not leave enough room above the valve to be able to just open in up, you have to do it with a wrench, which means it bleeds much slower. I guess I'll just open it up and let it bleed for several hours.

In regards to replacing the valve on the boiler, is it as simple as just taking the old one off and putting the new one on? Do I have to drain the whole system in order to get the pressure down in order to change it? (I plan on extending the above mentioned problematic bleeder valve out a bit so it's easier to bleed in the spring, so should I just plan on changing that valve at the same time)

Thanks again for the help, will update in the next few days.
 
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Old 02-17-14, 07:00 PM
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SD,
you'll have to take the pressure off the boiler to change the vent. If you're going to do work in the spring, I would every at once. Try to isolate as much as you can with that system.
 
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Old 02-17-14, 07:32 PM
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Monoflo systems are funny in that sometimes they bleed better with the circulating pump running and sometimes better when the pump is not running. You will likely have to do both. I disagree with Spott in starting at the farthest heat emitter but instead start at the nearest. My theory is that the air comes from the boiler and when it accumulates a large enough bubble it completely stops the water flow through the branch of the Monoflo tee.

Replacing the auto-vent on the boiler is just a remove and replace. You do need to close off the make-up water feed and drop the pressure to zero first. Make a
certain the power is turned off and the temperature is no more than maybe 110 degrees. Have the new vent ready, use Teflon paste on the threads and then unscrew the old vent with one hand and immediately screw in the new vent with the other hand. You will lose some water but it shouldn't be too bad. Might want to have an old towel or two on top of the boiler to catch the majority. Turn on the make-up water valve and turn the power on.
 
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Old 02-19-14, 07:50 PM
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Just as an update, I was getting some air out of one of the bleeders on the first floor and one of the bleeders upstairs. Last night, I was able to bleed the air out of the downstairs valve, but the upstairs one was still bubbling and spitting air.

I went back today and let the upstairs valve bleed for a good 3-4 hours. I still do not think I got all of the air out, but I got most of it at least. As of now, everything is working properly, but we will see if it holds up when the temperature goes back down next week.

One thing that I found peculiar is that earlier in the day, the temperature of the boiler was not reaching it's setting (180), and it was even dropping at times whenever I would set the thermostat higher for it to kick on, but it would heat back up whenever it would kick off. Once again, forgive my ignorance as I'm still learning the basics, but is this something else that I should worry about, or could the air in the system be causing it? Whenever I left, the temperature seemed to have returned to normal.
 
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Old 02-20-14, 12:49 AM
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The setting of most aquastats (the thermostat in the boiler water) are not all that accurate and they are often in a location that "sees" a different temperature than the thermometer bulb. Having the boiler temperature climb after the circulating pump stops is a fairly common occurrence. What is far more important than absolute accuracy is repeatability, the ability to consistently start and stop at the same temperatures regardless of the dial setting. The pressure gauge/thermometer of the boiler is also far from a precision device.
 
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Old 02-20-14, 07:50 AM
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SD,
The temp & pressure gauges aren't known for being very accurate but a good ballpark figure.
When the t-stat is satisfied and the boiler & pump shut down it is fairly normal for the temp to rise a little due to residual heat in the boiler.

When you turn the t-stat up and start the boiler, the pump also starts and replaces the hot water in the boiler with cooler water in the the rads to cause the lower water temp.
It is all very normal.

Be Well,
 
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