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Old 01-24-2013, 08:57 AM   #1
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Hydronic System Not Keeping Up With The Cold


Hey all,

During a recent basement remodel, the black iron pipe loop in my basement that feeds copper runs upstairs to the baseboards was replaced to gain ceiling height. A local HVAC contractor then installed Uponor Engineered Plastic manifolds - 8 loops, 1 feed, 1 return, pex in the basement connected to the copper upstairs runs. There is one zone (thermostat) in the house in the main floor hallway. House was built in '66, 1150 sqft cape.

System was working fine until this recent run of really cold weather in the northeast. Now the system just can't keep up. The thermostat has been set at 70 all week and this morning I woke up to a reading of 59. Baseboards are definitely still warm (although perhaps not as warm as I'd like), so all runs are definitely circulating water.

Feed manifold reads 155-160 degrees, return manifold reads 145ish. System pressure at 19 psi.

Through my own research it seems like the system is working properly. Am I just losing way to much heat through my walls? While my windows are probably about 10 years old, I'm guessing that the insulation is severely lacking. Would this be enough to cause this much heat loss? Knee walls upstairs appear to be insulated well enough (although could always add another layer of batt, wouldn't hurt).

Any other ideas to improve my system? Since pex is only rated to a max of 180 degrees, is this even hot enough to withstand temps in the single digits?

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Old 01-24-2013, 12:47 PM   #2
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Hydronic System Not Keeping Up With The Cold


Quote:
Feed manifold reads 155-160 degrees,
Ayuh,.... Turn up the hi-limit on yer boiler,...

Baseboard radiation likes it 'bout 180....
I think yer feed is to cold...

'n while pex is rated a 180, my OWBoiler runs nearer to 200, 'n I've had no problems with the pex, so far, 2 years runnin'....

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Old 01-24-2013, 12:57 PM   #3
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Hydronic System Not Keeping Up With The Cold


It sounds like the sum total of the new pex is may be smaller & more restrictive than your previous black iron. How often are the burners turning on & off when the thermostat is calling for heat and the boiler is unable to give you the heat you want? Do you know what temp the boiler was running at before the reno.

Since you've had reno's done, also make sure that the baseboard fins are all clear of dust. They only function as well as the air currents can run through them unobstructed.
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Old 01-24-2013, 01:33 PM   #4
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Hydronic System Not Keeping Up With The Cold


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Originally Posted by Bondo View Post
Ayuh,.... Turn up the hi-limit on yer boiler,...

Baseboard radiation likes it 'bout 180....
I think yer feed is to cold...

'n while pex is rated a 180, my OWBoiler runs nearer to 200, 'n I've had no problems with the pex, so far, 2 years runnin'....

I will look into turning up the heat. Maybe start at 170 and see if I notice any improvement. I was a tad worried about going higher since it says right on the tubing at 180 is what its rated for.

Natural gas furnace if that matters, btw.
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Old 01-24-2013, 01:34 PM   #5
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It sounds like the sum total of the new pex is may be smaller & more restrictive than your previous black iron. How often are the burners turning on & off when the thermostat is calling for heat and the boiler is unable to give you the heat you want? Do you know what temp the boiler was running at before the reno.

Since you've had reno's done, also make sure that the baseboard fins are all clear of dust. They only function as well as the air currents can run through them unobstructed.
The furnace isn't actually firing all that much. I unfortunately do not recall the old temperature, but I will try upping the temp and see what happens.

I will definitely be cleaning out the fins this weekend.
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Old 01-24-2013, 01:35 PM   #6
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Did he replace the pump at the time he modified the system? The impellers do wear out and reduce the flow----Just a thought from a guy that dropped in a new pump last week---cost $65---
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Old 01-24-2013, 01:59 PM   #7
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Did he replace the pump at the time he modified the system? The impellers do wear out and reduce the flow----Just a thought from a guy that dropped in a new pump last week---cost $65---
I'm pretty sure the pump WAS replaced. I also had the furnace checked/serviced a couple months after the system modification by a different company and they said everything was in order.
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Old 01-24-2013, 06:11 PM   #8
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Turn hi limit to 180. Your baseboard needs hi temp water.
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Old 01-26-2013, 12:46 AM   #9
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Hydronic System Not Keeping Up With The Cold


Yes, I can confirm I was having a similar problem, boiler temp was set at about 120* and I cranked up the temp to ~145 and now I'm able to beat back the cold! Now I have cast iron radiators, so not sure I should have it up that high, but the house couldn't get past 62* running non-stop, so had to! Any problems turning it up temporarily for cast iron radiators?
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Old 01-26-2013, 02:42 AM   #10
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You could turn it up to 160F without a problem for the cast iron rads.
The higher temps can exasperate pre existing thermocouple or pressure issues, but will not hurt a properly set up boiler system.
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Old 01-26-2013, 07:17 AM   #11
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Hydronic System Not Keeping Up With The Cold


alot of systems operate with pump running at call for heat....I like to set them up with an aquastat to control pump by tempeture of water so that even after t-stat is satisified pump continues to circulate hot water this makes them more eff...ben sr
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Old 01-26-2013, 07:50 AM   #12
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Cast iron rads are also on steam systems, which of course means 212 degrees of temp. Turning your water temp to 145 or higher won't harm them.
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Old 01-26-2013, 09:28 AM   #13
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Hydronic System Not Keeping Up With The Cold


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Originally Posted by Setzer1994 View Post
I will look into turning up the heat. Maybe start at 170 and see if I notice any improvement. I was a tad worried about going higher since it says right on the tubing at 180 is what its rated for.

Natural gas furnace if that matters, btw.
Ayuh,.... It's rated at 180, at 100 psi....

Yer system runs at Under 30 psi, 'n the rated temps at that pressure are well Above 180....

I'm runnin' 1" pex at over 200, at under 30 psi, on my OWBoiler...
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Old 01-26-2013, 12:11 PM   #14
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Originally Posted by Bondo View Post
Ayuh,.... It's rated at 180, at 100 psi....

Yer system runs at Under 30 psi, 'n the rated temps at that pressure are well Above 180....

I'm runnin' 1" pex at over 200, at under 30 psi, on my OWBoiler...

Thanks again, this was really helpful all!

Turned the internal boiler temp (no aquastat in the system, just one dial inside the burner) to 180, and now we're nice and toasty. Dial might actually be a little off because temp reading at the manifold only gets up to about 172, but its plenty warm now so I wont touch it further.

Thanks!

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