Heat not working???

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Old 03-19-14, 04:34 PM
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Heat not working???

I have a HVAC system...The heat stopped working on the 2nd floor of my house. My system is an oil fed boiler which provides hot water to 2 air handlers. One is located in the attic which controls 2nd floor and one in basement for 1st floor..the blower fan comes on when the thermostat is switched on but only cold air comes out from 2nd floor vents..I have tried to dissect the problem for two days and am not sure what the problem is...heat works well on first floor.. When I turned heat on on 2nd floor hot water rose to the attic pipes going into the air handler.. I figured that it might be the heating coils have frozen because hot water is getting to the unit...played with and reset the thermostat..I also changed the filter and reset the breaker to the unit and nothing..just cold air blowing....I opened the panel to the unit and look at the control panel...everything looks normal but I can't see the coils....turned off the switch located above air handler when working on it...today when I turned on the heat the pipes to the air handler do not get hot anymore so i am thinking maybe a pipe froze in the attic since yesterday..it has been about 25 the last couple nights..attic and pipes are insulated well.. Just insulated pipes in attic 2 weeks ago after pipes to air handler burst..I fixed them and heat was working fine for last 2 weeks until now...pressure in boiler is good..20 psi....first winter in house and house was built in 2006.. I have been trying to dissect this problem for a couple days now and can't figure it out.. Any help would be greatly appreciated..thanks i have come to the conclusion that it is either electrical or the coils have frozen...it's been about 45 during the daytime the last couple days.
 
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Old 03-19-14, 04:47 PM
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pressure in boiler is good..20 psi
But do you know if the pressure GAUGE on the boiler is good?

http://www.doityourself.com/forum/bo...ure-gauge.html

Your problem is almost certainly an AIR BLOCKAGE in the air handler water coil.

I'm sure that when the burst pipes were repaired that fresh water was introduced into the system to refill it. That fresh water had lots of dissolved air in it and after being heated has formed bubbles that have risen and collected at the top of the system.

You need to look around for air bleeders on the air handler piping and vent that trapped air. Once you get the air out, the hot water will start flowing again...
 
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Old 03-19-14, 05:19 PM
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Ok thank you..when the pipes burst a boiler technician who I have the oil contract came in as part of our service contract..he inspected everything including the pressure gauge and added some water to the system I believe..
Where would the air bleeders for the system be located?...would it be in the basement by the boiler?? I don't see anything on the attic piping unless it located actually in the unit itself...
What do the air bleeders look like and how would I know how much air to let out? Thanks
 
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Old 03-19-14, 05:32 PM
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he inspected everything including the pressure gauge
Yes, but did he actually take steps to VERIFY IT's ACCURACY? I bet not.

Where would the air bleeders for the system be located?
You need to find the ones that are INSIDE the air handler cabinet.

would it be in the basement by the boiler?
There may be some there, but operating those will do no good at all to get the air out of the pipes in the attic! That air is not going to go downhill no matter what.

What do the air bleeders look like and how would I know how much air to let out?
They look like, well, air bleeders!

There's all different kinds, but in general they would look like these:


image courtesy pexsupply.com,

Let ALL the air out.

What you should probably do since you have a service contract is to get the guy back that did the repair and tell him it's not working again. You paid for that repair I'm sure! Not covered under the contract I imagine, and I'm guessing that you paid enough for the repair that he should bleed the air out for free.
 
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Old 03-19-14, 05:49 PM
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Thanks I will try bleeding the system..the technician was there for free due to the contact I have with my oil company..he doesn't deal with HVAC though, just the boiler..lol. He replaced the gasket on the section valve in the basement bc it sprung a small leak.. That is why the pipe in the attic froze it the first place..it was 2 of the coldest days of the year...when the gasket blew heat shut off in the middle of the night.i caught it at 6 am before I left for work and immediately called my oil providers to send a technician..after gasket was fixed... Instead of letting the heat come up to the second floor for the house to get warm my wife leaves and turns the heat off...now the next morning when I get home from my 24 hr shift the pipes had burst..
 
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Old 03-19-14, 07:07 PM
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I already had the panel to the air handler open so I found the air bleeders easily...there were 4 of them..let the air out with a screwdriver..I heard only a little air come out...they were dripping cold water as well when I turned the screw..but not that much air escaped...anyway that did not work because the unit is still blowing just cold air when the heat is turned on...
Are you sure it was air blockage in the air handler coil? the heat was working well for over 2 weeks after the pipes burst and were repaired..also yesterday I felt hot water in the pipes going into the air handler...however the unit was still just blowing cold air out of all the upstairs vents..could it be a thermostat issue? The thermostat turns the blower on but no hot water is coming into the system anymore
 
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Old 03-19-14, 07:13 PM
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No, thermostat not the problem.

Did water come out under pressure like a lil kid peeing when you opened the bleeders?

I still question if there is enough pressure and possibly inaccurate pressure gauge on the system.

I suppose it's possible that it's froze up again, but I doubt it...
 
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Old 03-19-14, 07:28 PM
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Yes when I opened the first bleeder it came out under pressure as well as air hissing for a second or 2..I know this because it was pissing out on the electric so I was wondering if I should have shut down the water to the house first?..
I will try to check the pressure of the boiler tomorrow and see what happens...but I'm confused bc we there was just hot water going into the unit yesterday...doesn't make much sense..thanks for the help
 
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Old 03-19-14, 07:36 PM
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doesn't make much sense
I know... it never does!

I know this because it was pissing out on the electric so I was wondering if I should have shut down the water to the house first?..
Oh... you should cover anything electric so you don't get water on it!

Shutting the water to the house... NO, the domestic water supply has little to do with the pressure in the boiler. You WANT the bleeders to pizz. But letting WATER out does no good, you only want AIR to come out. Close them when the air stops and the water starts.

Air collects at the TOP of the system, such as in the air handler. An air bubble in the pipes will stop the flow of hot water and it will blow cold air.

Yes, sometimes the pipes leading up to the air handler will be hot, and this is a pretty good indication that it's NOT frozen.

Does your system have a separate circulator pump feeding each of the air handlers? If so, you may have had a pump failure.
 
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Old 03-19-14, 08:13 PM
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Cool

Yes thanks..I covered the electric...not much air came out of the bleeders..I will check the boiler gauge tomorrow..there is only one circulator pump....will let you know how it goes....
 
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