Overheat loop Fin-Tube Pitch Question

[djbutt]

I Need to install my overheat loop. Hopefully tomorrow.

I Will be using 30 feet of 1 inch copper fin tube with an automag.

I Understand hot water rises and cooler water falls, but where should my highest point in the loop be? Assuming the water cools as it flows through the fin-tube should highest point be at the begining of the first piece of fin tube then each section slope downward?

Would it be OK if the whole thing was level?

 

[Trzebs13]

I would think that you would want to go right from the boiler HX exit to the highest point. Then to your fintube that would be level or zig zag. (or what ever you have room for) then back to your intake. I'm sure some one else here can probably explain it better.

 

[Singed Eyebrows]

I Need to install my overheat loop. Hopefully tomorrow.

I Will be using 30 feet of 1 inch copper fin tube with an automag.

I Understand hot water rises and cooler water falls, but where should my highest point in the loop be? Assuming the water cools as it flows through the fin-tube should highest point be at the begining of the first piece of fin tube then each section slope downward?

Would it be OK if the whole thing was level?

I like to see a small cast iron radiator used for this purpose mounted above the boiler. Not sure how wide the sections of FT are, the more vertical they are the better for air flow. Can you elaborate a little better on the final fin tube shape? What will you connect it with & how far a run with this tubing or pipe? Randy

 

[ewdudley]

I Need to install my overheat loop. Hopefully tomorrow.

I Will be using 30 feet of 1 inch copper fin tube with an automag.

I Understand hot water rises and cooler water falls, but where should my highest point in the loop be? Assuming the water cools as it flows through the fin-tube should highest point be at the begining of the first piece of fin tube then each section slope downward?

Would it be OK if the whole thing was level?

Right, the highest point would be entering the fin-tube, and it would be where you need to bleed-off air, so at least a little downhill from there. Probably need some air space above the fin-tubes so air can convect up and away through the fin-tubes.

You talk about the first tube and then each section, as if they're in series. Since it's driven by gravity perhaps the sections of fin-tubes should be in parallel so as to offer less resistance to flow.

--ewd

 

[djbutt]

Thanks for the advice.

I ended up going with 5 7 foot pieces of 3/4 fin tube next to each other plumbed in parallel all horizontal directly over the boiler with a 1 inch drop from the hot end to the cool end.

Thanks again.

 

[rkusek]

[quote author="Singed Eyebrows" date="1287474985

I like to see a small cast iron radiator used for this purpose mounted above the boiler. Not sure how wide the sections of FT are, the more vertical they are the better for air flow. Can you elaborate a little better on the final fin tube shape? What will you connect it with & how far a run with this tubing or pipe? Randy[/quote]

How big of radiator would cover a 135k BTU boiler? I guess around 15,000 BTU is what it needs to dissapate. Sounds much easier than fin tube plus I know a scrap yard that has several of these. Didn't know how efficent they would be with thermosiphoning. I also wondered how 30 feet of fin tube would mount, guess five 7 foot sections in parallel would not be bad either. I've never been able to find that stuff as scrap here in Nebraska though.

 

[Singed Eyebrows]

[quote author="Singed Eyebrows" date="1287474985

I like to see a small cast iron radiator used for this purpose mounted above the boiler. Not sure how wide the sections of FT are, the more vertical they are the better for air flow. Can you elaborate a little better on the final fin tube shape? What will you connect it with & how far a run with this tubing or pipe? Randy

How big of radiator would cover a 135k BTU boiler? I guess around 15,000 BTU is what it needs to dissapate. Sounds much easier than fin tube plus I know a scrap yard that has several of these. Didn't know how efficent they would be with thermosiphoning. I also wondered how 30 feet of fin tube would mount, guess five 7 foot sections in parallel would not be bad either. I've never been able to find that stuff as scrap here in Nebraska though.[/quote] Yes, They don't need to be real big to shed enough heat. They make a nice simple install with lots of flow capacity(most are 1 1/2" pipe thread at least) & they cause a lot of air flow especially with 212 degree + water, Randy