my heat loss calculations (do these look right)?pic inside

Posted By 88rxn/a, Mar 3, 2008 at 9:24 PM

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1. #1

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
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i dont know if seems right or not??
i hope you can read it. im going to be installing the haydon 750 series baseboard heaters upstairs into 1 big loop on the outside walls of these rooms and the haydens are rated at

180F @ 4 GPM = 610BTU/hr
180F @ 1GPM = 580BTU/hr
this is rated on PER FOOT
if this seems right that means i need only 2FT of baseboard heater for the 1ST bdrm??? and then i need to run 8 FT of just the "frame " of the baseboard the rest?

2. #2

BrownianHeatingTech Minister of Fire 2. ```NULL ```

Oct 5, 2007
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Northwood, NH
I'm thinking you need to adjust the outdoor design temperature down a big. The outdoor design temperature is the coldest day of the year, and I expect it gets down well below 20 degrees in the winter in PA.

Joe

3. #3

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
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hmmmmm, i see....i guess i need to read the manual more... ill change it and see what the dif. is

**edit**
i found my elevation for the area and factored in the coldest day we had here. this made the 1st bedroom call for 3 FT now insead of 2.

4. #4

tuolumne Member 2. ```NULL ```

Mar 6, 2007
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I'm rather ignorant about such things...if you have exactly the amount of baseboard that's needed by the heat loss calcs. doesn't that mean you will need to run the pump continuously at that outdoor temp? Is that the typical design approach?

5. #5

BrownianHeatingTech Minister of Fire 2. ```NULL ```

Oct 5, 2007
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It depends on the calculator. Last time I used Slant/Fin's software, it came up a good bit higher than others, so I think they have a safety factor built into it.

If the software (or your manual calculations - still a lot of guys who do it by hand) doesn't include a safety factor, then you should add some to the radiation. That has the effect of lowering the water temp requirements, which improves efficiency. You just don't want to go overboard, because you'll short-cycle the system.

I'd suggest planning for 140-degree water, and calculate the lengths that way.

Joe

6. #6

tuolumne Member 2. ```NULL ```

Mar 6, 2007
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Thanks for clearing that up Joe. When I did mine, I used water temperature as the safety factor. At 140 degrees my wall panels would need to run most of the time at 15 below zero, but giving them 180 degree water would cut that way back. My wood boiler/storage setup will output hot water anyway, but if I add a Munchkin down the line I will be running the temps up and down with outdoor reset. Sorry for asking a question in someone's thread. It actually hit 20 below zero here a few days ago, and it is currently 52 degrees!

7. #7

mtfallsmikey New Member 2. ```NULL ```

Nov 27, 2007
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Mt. Falls Va.
I would lower your design temp down...and with using a wood boiler, go a little strong on the baseboard in case supply temps go a little lower. BTW, how much is Haydon BB there? My quote from wholesaler is around \$6.50 / ft.

8. #8

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
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price here is around \$7.50/FT.

i lowered the temps to -10 (outside temp) and changed the water temp to 140. i dont know what these (baseboard) will flow at those temps. ill need to call and ask.
i to am ignorant to ALL of this. im really glad this forum (and you people) are here to help! after lowering these ideas, i got just under 4FT of needed baseboard for the 1ST bdrm.
ill call and find out what the BTU's are for 140 tommorow.
now i just need to figure out what size a pump to run (using 3/4 PEX)!
i thought i read somewhere on here i need to run a plate exchanger since its higher than the boiler and make it a seperate cycle?
thanks everyone.
ill post my results tommorow.

9. #9

BrownianHeatingTech Minister of Fire 2. ```NULL ```

Oct 5, 2007
1,253
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Loc:
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How many total feet of baseboard, and how many total feet of pex?

It doesn't sound like this system actually requires 3/4" pex, and 5/8 could be used instead (somewhat less expensive, and more flexible), although it wouldn't hurt anything to use 3/4"...

Depends if the boiler will be an open or closed system. Open systems and closed systems need to be separated by a heat exchanger. If the whole system will be closed, then there is no need for a heat exchanger.

Joe

10. #10

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
northeast PA
oh i see. the biulder said the boiler can be setup for either pressureized or non (and closed is non pressurized isnt it?).
and i havent quite figured out how much PEX i need yet. but i already have the 3/4 PEX that was given to me for free. cant beat a free 100' roll of 3/4 PEX!

**EDIT** and the haydon 750 is about 150BTU/HR @ 140F water temps
that puts me just over 4FT of needed baseboard. so maybe i should get 5FT or 6FT of baseboard and the rest just the cover correct?? of course placing it under the windows would prob. be best right?

11. #11

BrownianHeatingTech Minister of Fire 2. ```NULL ```

Oct 5, 2007
1,253
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Loc:
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Closed is pressurized. Open is non-pressurized.

Under the window would be best.

Make sure that running at that temp won't make any other pieces of baseboard on the same loop too large. Don't need to plan one room for 140, and find out that the next room over doesn't have enough wall space for the baseboard needed to run at that temp.

Also, remember that there will be a temperature drop as the water flows. Figure 20 degrees from the start of the loop to the end of the loop, so plan your flow direction and add some length to the rooms at the end.

Joe

12. #12

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
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ok, i see. so lets say i use 5FT (when it calls for 4FT) in the 1st bedroom. the 1st bedroom is the begining of the loop (after the water travels from the pump of course) then the excersize room is the 2ND and the den being the 3RD and final room. should i add 1 extra foot to the excersize room and 2 FT in the den to be safe? being the size of the other 2 rooms, there is more than enough room to add baseboard instead of just the cover.

13. #13

BrownianHeatingTech Minister of Fire 2. ```NULL ```

Oct 5, 2007
1,253
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Loc:
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Without all the details, that does sound like a pretty good "ballpark" for it.

If you find out when you get into your first heating season that one room is running a bit hot, you can always snip some of the fins off of the tube. Remove 4" of fins, then see how it feels for a couple days. If it's still warmer than the others, repeat. Old-school heat balancing...

Joe

14. #14

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
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ok thanks alot, you been very helpful!

15. #15

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
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so here is what i have so far, all the baseboard for the first room and half the 2ND with the rest on the way (backorder). so say i ran this a closed (pressurized) system. do i need any relief valves or anything like this upstairs at the begining or end of the baseboard loop? i wasnt sure if i needed anything before i started crimping,cutting, soldering the stuff for upstairs yet.

16. #16

Bob Rohr Minister of Fire 2. ```NULL ```

Jan 9, 2008
1,131
164
Loc:
SW Missouri
All three rooms on 1 zone I assume? You could home run them to a manifold and be able to zone them if desired. 1/2" pex would handle that. Pex al Pex is nice for baseboard, much less expansion and it holds it shape. With regular pex allow for expension and supports to allow movement without squeaks. Actually insulating the lines help with piping loss and make support noise go away.

Also the dampers are usually adjustable to regulate heat output instead of cutting fins. Less bloodshed also

hr

17. #17

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
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yes 1 zone. the house is 90% finished besides the kitchen. that is the only exposed (studs) wall i can run through. the wall is right at the bottom of the stairs which leads to the first bedrooms closet and i can remove the trim along the stairs for the return.
i wasnt sure if i needed some kind of relieve valve or anything upstairs before i started putting it together.

and thanks for the idea, i was gonna insulate all feed lines going to the upstairs.

18. #18

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
northeast PA
any suggestions to previous post?

19. #19

BrownianHeatingTech Minister of Fire 2. ```NULL ```

Oct 5, 2007
1,253
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Loc:
Northwood, NH
No, you don't. You should have an air eliminator at the pump, but there is no need for a vent anywhere else.

Joe

20. #20

88rxn/a Member 2. ```NULL ```

Feb 12, 2008
145
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Loc:
northeast PA
thanks brown. you have been a BIG help!
not much has been done latelty...i was thinking of making the upstairs a closed system with a plate and run the rest open. also, instead of running the PEX under the floor for radiant heat...i have a system(lennox upright register) in the cellar that isnt hooked up yet. i thought about running a plate to it also and run the ducts throughout the downstairs and hook the gas to it for a back up. i know radiant heat is the best but for my budget i may have to go this way....

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