diy hydronic heat install


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Old 02-17-15, 08:00 AM
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diy hydronic heat install

OK tell me if I am taking on too much or is this a DIY project. I presently have a gas pack with propane furnace and AC unit. all mounted outside. I want to install hot water base board heat. I can install baseboard heaters and pex (oxygen barrier) I would buy the heaters and install . Its a 1900 sq ft house and I would use 2 circuits. I would run the in and out pipes to crawl space and plan to install a Propane fired Lynx combi hot water boiler with 2 taco pumps. I am capable of plumbing and have the tools. I have recently rewired my house with inspections. I am 75 and my crawl is 5' where I plan to put boiler and goes down to 2' at the far end. I would use all 3/4 " pex with copper going from baseboards thru floor then go to pex. Is this a good plan? what do I need to change. The boiler is high efficiency with PVC exhaust thru crawl wall.
 
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Old 02-17-15, 12:28 PM
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The 3/4 inch PEX (with oxygen barrier) would be okay to individual baseboards but if you are going to run several in series then I would use 1 inch. You could use a manifold arrangement with the 3/4.

I am 75...
Only you and your doctor can determine if you are "up" for this project. I'm still a few months shy of 65 but I would not undertake such a project. Then again, I DO have several significant medical problems.
 
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Old 02-17-15, 12:40 PM
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You're going to put a boiler with two circulators in a crawl space ?
 
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Old 02-17-15, 12:44 PM
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I'm still a few months shy of 65 but I would not undertake such a project.
I'm younger than Furd (not much) and bperry (a fair bit), and I wouldn't attempt it alone. With some strapping young lads to help (read this as listen to me bark orders and obey) I might give it a shot.

Make sure that your local code officials are OK with installing a boiler down there... and check the install manuals for proper clearance all around.

Is it a DRY crawl? Concrete floor? If it's damp, don't expect a long life out of that boiler.
 
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Old 02-17-15, 01:20 PM
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Yes I plan to put a high efficiency condensing boiler with PVC exhaust and circulating pumps in a 5' tall crawl. Boiler will be on a concrete pad. Actually guys I am 75 but still very active and only meds are vitamin d and aspirin and a celebrex 100 mg. Thankful for health. I still am a home inspector also. I know this is a large project but I feel I am up to it. Just wanted to know if my plan sounds OK. Trying to calculate how many baseboards I need. Also am pretty close with our county inspector. There are several homes around here with gas furnaces in crawl space. My crawl is flat and dry. already have a water treatment system under there to remove iron. I installed it also.
 
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Old 02-17-15, 01:44 PM
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If you feel up to it, then go for it!

What you want to do is a HEAT LOSS ESTIMATE on the home, also called 'Manual J', on a room by room basis. When you know the heat loss of each room, you can select the amount of baseboard based on that.

Typical Slant-Fin FineLine 30 is rated at about 600 BTUH per foot (NEW! I always derate the output for dust buildup, etc) I'll use 550 BTUH per foot.

If a room has a heat loss of 5500 BTUH, then you need to install 10 feet in that room.

The room by room heat loss is important because you want the amount of baseboard in each room to be PROPORTIONAL to the heat loss so you don't have some rooms cold and some too warm, and only one or two rooms where Goldilocks would be happy.

If the Lynx is a MODULATING / CONDENSING boiler, you want to install MORE BASEBOARD in EQUAL PROPORTIONS in each room so that you can take advantage of the extra efficiency of the boiler when it's condensing. Once you need water over 140F to heat the home, your boiler is on the edge of condensing and the extra efficiency is out the window (or the flue pipe) once it stops condensing.

Check the SlantFin BTUH output tables. You'll see that they rate the baseboards at lower water temps too... the number above is with 180F water. If you use the number for say 140F water when you figure how much you need in each room, you will come out with more footage, but you will be able to take advantage of the condensing boiler's extra efficiency for a greater part of the heating season.


Doing the heat loss also lets you size the boiler correctly. There's no point installing a bigger boiler than you need!
 
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Old 02-17-15, 01:54 PM
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Yes... I just checked. The Lynx is in fact a MOD/CON boiler.

The rating for S/F FineLine 30 at 140F water is 340 BTUH output.

So, for the previous example room with a heat loss of 5500 BTUH you would need to install 16 feet of baseboard versus the 10 feet if running at 180F water.

There are higher output baseboard units available also. If you can't fit the amount of baseboard you need to run with the lower water temp, go with the high output stuff.

For example, the Multi/Pak 80 with the H1 element is rated at 460 BTUH at 140F water.

You would only need 12 feet of that in the example room.
 
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Old 02-17-15, 04:40 PM
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If the you have a Conditioned crawlspace; yes maybe but a vented crawlspace no, bad for the electronics and wiring.
$0.02
 
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Old 02-18-15, 05:45 AM
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Thanks for all the input. I have done a room by room heat loss and I was under the impression the boiler delivered 160 Deg water. I am talking to the distributor today and will get more info. As for as crawl space I have had a water treatment system under there for a year. it has a control and timer on top and so far it still looks new. Thanks again for all the input.
 
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Old 02-18-15, 07:45 AM
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I was under the impression the boiler delivered 160 Deg water
I'm sure it will go all the way to 180F if it needs to and you let it.

Thing is, once the return water to the boiler goes above that 'magic number' of appx 135F, the boiler will stop condensing and you will use the extra efficiency that you pay for in a mod/con.

So, the point is that you want to design such that the return water never needs to go above 135. This means that if you design for a 20F delta T between supply and return that your supply could be as high as maybe 155F.

BUT, the lower the temp, the more it will condense and you will take full advantage of that feature.

If you design for 140F you can be sure it will condense all winter long...

Design for 150F and it might condense 95% of the winter...

etc
 
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Old 02-18-15, 10:14 AM
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Boiler System Efficiency [pdf]
By Thomas H. Durkin, P.E., Member ASHRAE 2006 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Journal (Vol. 48, July 2006).
 
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Old 02-18-15, 11:26 AM
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well I talked to rep. Going with the Multi/pak 80 and the default on boiler is 175 Deg but is adjustable down to 150 or up to 185.On a slab in crawl is OK for my area just have to install a condensate drain box with pump to pump into drain. So now I have to recalculate how many heaters I need. Also found if I have a small room Like a bath I can use the lower priced heater. Think I will stick to all 1 kind.Thanks for the help. I will let you know when I receive my material and get started. looks like 6 to 8 weeks.should fit in with spring and better weather.
 
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Old 02-18-15, 12:14 PM
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well I talked to rep. the default on boiler is 175 Deg but is adjustable down to 150 or up to 185
That must be the 'top end' adjustment of the heating curve, the HIGH LIMIT, or BOIL MAX, whatever that parameter is called in Slant/Fin lingo...

The control will absolutely 'target' even lower temps... all the way down to room temperature...
 
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Old 02-18-15, 12:46 PM
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heatworm thanks for the info good reading, lots of info.
 
 

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