boiler does not get hot enough

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  #1  
Old 01-08-18, 08:56 AM
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boiler does not get hot enough

I have an old boiler that heats water through a hydronic system. The pump was replaced but it still does not heat up the house properly. When I call for heat downstairs, the temperature drops from 180 to 140. When the upstairs calls for heat the temperatures remains steady at 180 but it never gets warmer than 62 degrees. Air was purged from the system too. What can be causing this issue?

the return line for the downstairs line is not even hot.
 
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Last edited by mykim; 01-08-18 at 09:23 AM.
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  #2  
Old 01-08-18, 09:26 AM
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mykim -

I'm not one of the experts here but it certainly sounds like your are not circulating water to the second floor. That's why the water temp stays at 180 - you are not transferring heat to the second floor. But it sounds like it's not a pump problem since you have a single pump and the first floor is fine. You must have zone valves.

I think you should get ready with zone valve information because I bet the experts will ask for that first.
 
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Old 01-08-18, 09:33 AM
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i do get heat upstairs, just not downstairs. the zone valves are made by honeywell
 
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Old 01-08-18, 09:53 AM
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If you turn the 2nd floor thermostat all the way down to keep that zone out of the picture. Then turn the first floor thermostat up to call for heat, the burner should keep the water hot while it is circulating through the first floor.

The burner would shut off at 180 if that's what the high limit is set at, but it should come back on long before the water reaches 140 to keep the water hot while it is circulating - provided that the first floor thermostat is still calling for heat.
 
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Old 01-08-18, 10:12 AM
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it used to be able to maintain the heat when both zones called for heat. Now the heat just drops when the first floor calls for heat. I don't know why its doing this. I turned the heat off for upstairs but im not sure if its making a difference. the temperature still reads at 140, which is not hot enough to warm up anything
 
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Old 01-08-18, 10:29 AM
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Now the heat just drops when the first floor calls for heat.
.........................................................................

Do you mean the boiler water temperature drops from 180 to 140 as you read the boiler gauge? And this only happens when the first floor calls for heat? In other words, you read the boiler temperature and it's 180. Then you turn up the first floor thermostat and you see the boiler water drop to 140 over a period of time? But during this period the burner does NOT come on?
 
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Old 01-08-18, 10:42 AM
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yes the water temp drops from 180 to 140 when i call for heat in the first floor. The burner is on when i call for heat so it cant be that.
 
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Old 01-08-18, 11:11 AM
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I think this is beyond me. Need one of the pros to jump in.

If the burner is running but the water is not getting hotter than 140, then I would think that would mean you are losing an enormous amount of heat from that water somewhere. If the heat was being transferred to the zone from the water as the water circulated then the zone should heat up. But it's not!

If the pump is turning ON as required but the boiler isn't being called from a control to heat the water, I think the water temperature would drop rapidly as the water circulated and then would not heat up any higher and that would explain things - EXCEPT you are seeing the burner come ON. Doesn't make sense to me. Hope one of the pros jump in.

wonder if the zone valve for the 2nd floor is stuck open? But I would think then that that zone would get hot - oh well!! I think the guys who know will be along
 
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Old 01-08-18, 12:42 PM
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m,
You said you bled the system of air which is telling me you are getting full flow through the zone so eliminate frozen pipes.

You have 1 pump and the same boiler and control are common to both zones and one zone and the boiler are working which leaves your zone valve which are the only parts that run idependent of each other.

The problem more than likely lies in the zone valve or in the stat that controls it.

You can jump the 2 wires on the stat and see if that opens the ZV and turns on the boiler. If that doesn't work you can do this.

Your ZV has a lever on it for manual operation. Move that lever in the opposite direction it is now with the stat turned up to call for heat. If the ZV is working the lever should move without resistance. If you encounter resistance that means the ZV is either not getting the call for heat (t-stat) or the ZV is defective.

With the lever in the manual position you should get heat to that zone,

If that turns out to be the case if you leave that on manual every time the other stat calls both zones will heat.

So that way you can still heat the house until you the ZV replaced.

Hope this helps a little.
 
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Old 01-08-18, 01:46 PM
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yeah downstairs zoning valve has resistance when i push it and It is in the auto position now. But somehow, the ambient temperature is up to 63 degrees now. however it took hours to go from 49 to 63. The plumber who was here earlier said that the zoning valves were operating correctly but im guessing he is wrong?
 
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Old 01-08-18, 06:07 PM
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If it happens again and you cannot get heat when the stat calls put the lever to manual and turn up the other stat and if you get heat to both zones I would change the ZV or leave it that way for the tech to look at.

The tech should be able to check the stat and ZV with his meter to see what's going on.
 
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Old 01-14-18, 04:27 AM
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It is time to call in a professional and have them check the gas input and to adjust the primary/secondary air to the burner. They can also check all the operating and safety controls to make sure that the boiler is operating properly and efficiently. My guess is that the gas regulator is in need of adjustments or there is something not allowing the unit to fire at full and efficient input. I did not see where you said what type of heat radiators you have in your home. (cast iron rads or copper finned baseboards) Also make sure that the radiation is clean.
 
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