Hydronic Baseboard Issue

aplewis1

Last year I had a new furnace installed and added a 8' high output baseboard into the system. My boiler is currently oversized as heat was never ran up stairs and my plan is to add a second zone in the near future. My current system is a combination of baseboard and radiators. The issue is last year when I fired up the furnace after install the new baseboard was extremely hot. Rest of the system seemed fine just this one room you couldnt stand to go in there it was so hot. The room itself is 14' x 18'. I called the plumber to come out and take a look so he changed some settings in the programmable controller on the furnace. Time went on multiple calls to plumber finally we hit a sweet spot on the programmable controller to where it would keep the house warm but that new baseboard will not heat up. I hit it with a thermal camera and the elbows are around 175 degrees at the feed and return but its only reaching 72 degrees at the fins? The system is one single loop. Everything else works fine.

Intplm.

@aplewis1 Best thing to do is offer up some pictures of the system close up and farther away. The controller and piping near the boiler etc.
Post them here so we can take a look.

aplewis1

Will do I will post up some photos later.

Jamie Hall

Sounds as though at first you had too much flow in that baseboard -- and now you may not have enough?

aplewis1

aplewis1

aplewis1

aplewis1

Hope that will shed some light on my situation.  Again the system is one loop no bypass valves. Piping is a combination of 3/4 copper pipe and 3/4 pex.

mattmia2

How do the basebaord and the radiators connect to the system, show some of that piping.

aplewis1

inlet

aplewis1

outlet

aplewis1

The gray pex basically goes through the floor and hooks straight up to a 3/4 copper pipe on both the feed and return lines.

aplewis1

mattmia2

How are the ci radiators fed?

aplewis1

aplewis1

mattmia2

is it all just plumbed in one loop or supply/return mains, or what?

aplewis1

aplewis1

It’s all one loop piped with 3/4 copper and pex.  Straight out of the boiler and straight back into the boiler.  The pictures posted show how it comes out of boiler and how it returns to boiler.  In the photos the black iron is my propane line and the white pex is just a drain.

mattmia2

You will probably have to put a bypass with a balancing valve or a TRV on the fin tube and play with the supply temp to get it to even out. Be even better if you did one of those things and replaced the fin tub with something with more mass like a ci radiator or at least a panel radiator.

the copper fin tube baseboard heats and cools quickly, the cast iron filled with gallons of water gives off heat for a long time after you stop pumping hot water in to it.

LHthread

How high is the new added baseboard above the boiler ?
I see no manual vent, Coin Vent on the baseboard?
On the cast radiator, why is the pipe at the top of the rad, and No manual air vent ? I piped HW on Cast inlet and outlet on the bottom bung openings. Not on the top.

EBEBRATT-Ed

@mattmia2 is right . Mixing fin tube with cast iron on the same loop is not a good idea.

hot_rod

How much 3/4 pex in the loop? That is adding some flow restriction, between the smaller ID and the insert fittings.

aplewis1

The entire loop is below boiler level.  There is only around 20’ of pex being used just from the new boiler to the existing 3/4 copper lines where they tied into the system.  The system has operated well with the old oil boiler with a combination of old baseboard and radiators for years.  Obviously the baseboards would be extremely hot as they don’t need the temps that a radiator needs.  I moved the location of the new propane boiler to the first floor of the home and put it in the closet of our foyer.  Basement is prone to flooding.  The system worked great with that particular baseboard in question but it was way to hot.  Now even with the inlet temperature being 172 degrees the baseboard is only heating up to around 70 degrees.  I verified temperature at the fittings entering and leaving said baseboard with a flir IR camera at 172 degrees +/- 5 degrees.  How is it that the incoming hot water will not make the baseboard 172 degrees or at least close to it depending on ambient temperatures?

mattmia2

You probably need more pump(or to replace the 3/4 pex with 1" pex or 3/4" copper or both. 3/4" pex is significantly smaller than 3/4" copper, 1" pex is about the same id as 3/4" copper). The old system probably had enough velocity to move all that mass of water fairly quickly to heat it all fairly evenly, the new system probably does not so the first few radiators get most of the heat and the water is not very hot by the time it gets to the fin tube. If you let it run for hours or kept the pump on constant circulation they temps would likely eventually even out as all the radiators before the baseboard heated up.

If that boiler has a post purge setting for the heat, you can try setting that to maybe 15 or 20 minutes to more evenly distribute the heat.