Troubleshooting not enough heat

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Old 12-14-13, 12:16 PM
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Troubleshooting not enough heat

I have a Rinnai E110C without hot water unit. The house doesn't get warm enough in 15-20 F temperatures. I have two zones, one for each floor. Both floors have heat, but not enough.

Expansion tank feels cold, supply line is hot (170 F), but return line is only just warm. I'd guess the delta-T at the boiler is more than 50-60 F. Pressure is 20 PSI. Pipe is hot past both zone valves.

Is this possibly due to air in the pipes? I don't hear any gurgling noises, but I do hear a faint kind of musical "boop" sound, about once every 5 seconds sometimes.

Or is the circulation valve not pumping water fast enough for some reason?
 
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Old 12-14-13, 12:45 PM
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What kind of heat emitters? fin-tube baseboard? or is this in-floor radiant?

If baseboard, how many feet of fin-tube element on each zone?

Have you lived through a winter with this unit yet? or is this your first? Give us some history.

In other words, did it work properly LAST winter?
 
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Old 12-14-13, 12:58 PM
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Yes, it was sufficiently warm before. I had it installed about a year ago in late Dec/early Jan, so it has gone through one winter.

I have fin-tube baseboard. I don't have a tape measure handy, so I'm not sure how many feet, but I'll post that information after finding my tape measure.
 
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Old 12-14-13, 01:06 PM
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In that case I might suspect that the circulator pump is not pumping and the flow in the system is by gravity only.

Even just a ballpark estimate of how much baseboard is what I was looking for... doesn't have to be exact. And the fact that it worked well last winter makes the measurement of the baseboard non-essential.

Can you tell if the circulator pump is running or not?
 
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Old 12-14-13, 03:19 PM
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Well, I felt the circulator and it felt hot. I think that it had a faint hum/vibration, but it could have been my imagination.

I did some reading up, and discovered that since it's a condensing boiler, it will try to keep the return temperature low (like 130 F or so). I also noticed that the return from the upstairs is colder than the return from downstairs.

I'm going to try reading the manual more carefully and figure out how to get more diagnostic info out of the boiler. Turns out it does sense the return temp, so I'll be able to know for sure what it is. It may also be controlling the pump speed (to a finer degree than just on/off).
 
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Old 12-14-13, 04:30 PM
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discovered that since it's a condensing boiler, it will try to keep the return temperature low (like 130 F or so)
Well... sort of... but it does that by regulating the SUPPLY temperature and you said that was 170 I believe?

No, you should NOT have a 50-60 delta tee on your system.... you should have maybe a 20-30 at most.

To me it sounds as if your pump is not pumping. It may be getting power, it may be hot, it may vibrate, but still not be pumping.

What is the make model of the pump?
 
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