Hot water baseboard with return inside

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Old 11-05-13, 06:15 AM
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Hot water baseboard with return inside

Bringing an old thread to life!

http://www.doityourself.com/forum/bo...rn-inside.html


I have that setup.... the big box contractor grade Slant Fin and a 3/4" return line resting on top of the fins.

It's never put out a lot of heat, considering, and have oftentimes thought of replacing it with a more robust product. The line has to return the way it came. It's in a room that's minimally insulated (3.5" fiberglass in walls and 6" ceiling with antique windows) and above an unheated dirt crawl space spanning two stone foundations.

Is there a way to minimize the loss with a return pipe contained within the heater?
 
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Old 11-05-13, 06:27 AM
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Is there a way to minimize the loss with a return pipe contained within the heater?
I think its actually better. I would think you would have more heat output with the pipe being looped back..

Possibly you do not have enough baseboard in that room if what your saying is its colder then other rooms.

Best way is to do a heat loss of that room... How many sq ft is the room? That will tell you how much baseboard you need...
 
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Old 11-05-13, 08:00 PM
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I agree with Mike, there is no "loss" from having the return double back over the fins, unless perhaps the entire unit is humongously long, fifty feet or more. If the room is cold you need more baseboard, a high output baseboard or better insulation and air sealing.
 
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Old 11-05-13, 10:04 PM
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What temp. are you running through the baseboard. They are rated at about 550btu's a ft.@ 180 deg. Everybody trying to run the boilers at lower temps. these days but remember the lower the temp. the lower the output. As far as runing inside returns I've had to do that many times with no apparent effect.
 
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Old 11-08-13, 07:58 AM
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Found it!

I was looking for the old thread I resurected.... somehow this became a new thread!

My concern was that a 3/4" return pipe resting on top of the fins would be detrimental to the convective air flow, thereby cutting down the output.

The rooms a a mess via design. It's a converted three season room single floor area dating back to almost the Civil War with what I think was a wrap around porch that's been enclosed and somehow merged with the room and the whole "S" shaped area is now our kitchen. It's on a combination of seemingly three foundations, and what appears to be a wind barrier cemented pile of cobblestone supporting nothing. It's insulated as well as practical. I tried insulating the rim joists, but all they did was fill up with mouse poop etc so I removed it. I had the walls open 15 years ago and added 3 1/2" of fiberglass and the ceiling has 6" rolled out. The floor is cold, the room's always chilly (good excuse to bake!) and I don't know if the return pipe is limiting the effectiveness of the fin tubes convection. I've been thinking about putting in higher rated fins in that room, but regardless need to know about the return pipe position.

I must add that the main house is two stories and spectacular. This one story area I described on the backside is pathetic by modern construction standards, but we've made it a wonderful living space. I don't want to make it sound like we live in a shack with mice.

The water temperature is controlled by ODR and ranges from 135 to 180. There are about 35' of fins in the room.
 

Last edited by thatoldguy; 11-08-13 at 08:14 AM.
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Old 11-08-13, 04:59 PM
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Although I have run baseboard that way I have always raised the pipe above the fins and never rested them right on top, partly for that reason. If you look at your brackets that hold the element on the top part there's a cutout like a half moon. The purpose for that is to have room to run a pipe and they used to sell little hook hangers just for that purpose. We just used wire most the time.
With 35 ft. of baseboard, that's equivalent to about 19,000 btu's of heat. Not knowing your room dimensions or construction I can't say if it's enough but that's a lot of heat in one room.
I think if it were me I'd be more concerned with your ODR. Although you have 35ft that 19,000 btu's is only at the 180 deg. water. It is a lot less at 135. Before I went with the high output I would try running that baseboard at 180 and see how it works.
Those ODR's are fine if you put them with a new system and everything is sized for that application, but for an older home where the heat was figured for 180 they may not be beneficial.
 
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Old 11-08-13, 05:23 PM
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Those ODR's are fine if you put them with a new system and everything is sized for that application, but for an older home where the heat was figured for 180 they may not be beneficial.
In principle I tend to agree with this statement, more or less...

BUT...

During the 'shoulder seasons', like now... fall and spring... we certainly don't need to run the water up to 180 to get enough heat output.

If the system is designed for 180 water, we need to remember that the DESIGN DAYS for a system might only be 2 or 3 days during the mid-winter when the outdoor temp really IS low enough to require that hot water. For 90% (or more) of the heating season we can get along just fine with cooler water.

The "Widder Lady" next door called me in a panic a few years ago...

"I have NO HEAT! My upstairs bedroom carpet is SOAKING WET!"

It turned out that the 'return pipe' that was run above the heating element had ever so slowly been SAWED THROUGH by the bracket that the pipe was resting on due to the expansion/contraction of the pipe over the years.

I would recommend doing whatever it takes to avoid this happening to you! She had to replace the carpeting and some of the subfloor because it had been slowly leaking for YEARS apparently before the hole got big enough to let enough water out and cause a problem (compounded by the fact that her pressure reducing valve had ALSO bit the dust and was not feeding water any longer).

Don't let those copper pipes rub on steel brackets!
 
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Old 11-08-13, 06:02 PM
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Trooper is right about the the brackets. You want to suspend the pipes below the brackets.
As far as the ODR goes he is also right as far as saying there are only a few times a year we need full temp.(180). My point was that before you spend the time and money to go high output you may reach the same result by raising the temp. in what you have.
Slantfin rates there board at 580btu's p.f. @ 180deg., 35ft 580= 20,300 btu's., @ 135deg.= 295btu's p.f.
35 x 295=10,325 btu's. That's cutting you heat output in that room in half. Is that enough to do the job. I don't know if you've looked at the price of baseboard lately, especially high putput. It might be a lot cheaper in the long run to raise the temp.
 
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Old 11-08-13, 06:09 PM
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Slantfin rates there board at 580btu's p.f. @ 180deg.
And that's for BRAND NEW baseboard. Over the years dust collects in the fins... even if the lady of the house uses the vacuum cleaner as much as mine does.

I would not be at all surprised to learn that a thin layer of dust would cut the output by 30% or so.

I always stress that the fins be kept as clean as possible... it's amazing how much of that capacity will be lost to even a thin layer of dust. It's a chore to keep them clean (especially if there are pets in the home!) but the rewards are there...
 
 

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