Double Fin Tube Btu Output??

Jim_65

you both for the quick responses.

Brad what you said makes sense especially with the pre-warmed air scenario. I will run my calcs off of this info.

Thanks again.
JF

Jim_65

Double Fin Tube Btu Output??

I looked at a project this morning and came across some Double Fin Tube/Element Baseboard. The connection piping is 3/4" and the fins (fin) are 2" Width x 5-1/2" Ht. This particular fin is one piece unlike many others I am familiar with where they are just stacked on top of one another. The enclosure is 2-3/4" Width x 8" Ht.

My question is does anyone know what the Btu output per linear foot would be with 1 GPM at an average water temperature of 170*?

Or, if anyone is familiar with this style and could provide information would be helpful as well.

Thanks in advance!

Jim French

Brad White_9

Normally

I would take the total of both tiers at between 130 and 150 percent of a single tier of that type. The reason is that the second tier sees warmer air (less delta-T) having been pre-warmed.

Absent any certified manufacturer data, that is what I would assume.

So if your basis is 500 BTUH per LF, you might get 650 to 750 out of it, per foot.

ALH_4

Double Tier

Seems like the output would be close to Argo Panel Trim baseboard. Why don't I see baseboard listed on Argo's website anymore?

-Andrew

Dan Joyce_4

Double tier

I'am looking at a Slant/Fin commerical fin tube radiation catalog, dated 1990. Multi/pak 90 shows, 1" copper,alum fin,at 180f,fr 3 ft/sec has btu/hr of 1375. Two tier btu/hr of 1500.That's about 12.5%.
Jim, how do you get 2 5" high elements in a 8" enclosure?
Brad, While the S/F bb is much larger wouldn't the princpals stay the same ie 12.5%

Dan

ALH_4

How about this?

I knew I had it here somewhere.

To determine your output in btu/h per foot of bb enter your fluid temperature in deg F:

Double Tier:
Output=11.08*(Fluid Temp) - 1036

Single Tier:
Output= -.0006*(Fluid Temp)^2 + 8.6369*(Fluid Temp) - 803.39

In this case it turns out to be something like 28% more output for double tier.

-Andrew

Jed_2

Argo Panel Trim

baseboard is like any other residential "double tier" baseboard (outputs vary per mfg specs, and Argo's is rated a bit higher), but they all are series loop tiers. Hence the 2nd tier output derating. But those pics are in parallel, hence no SWT temp drop per tier. It's like a Beacon Morris headered convector, except the fins are connected to both parallel fin elements. Now, the 2nd tier is supplying the same water temp as the lower one. That doesn't happen in a return, series double tier arrangement. I've never seen this type of "baseboard fin element". Of course the 2nd tier element in a series double tier BB will see a bit lower temp, hence the fractional total output rating. I'm no Engineer, but it seems to me that the 2nd tier of this parallel fin tube will put out an accelerated air temp, simply because of the SWT. It's not a U-tube double tier baseboard. It's a convector. And, yes, the cabinet convector headered elements are horizontally parallel vs. vetically, and chimney effect comes into play. But, SWT?

Thoughts?

Jed

Jim_65

Dan

Sorry if my post may have been a little confusing.

But, this is one complete fin total (not two fins). So, the specified fin size of 5-1/2" is for the total height/fin area. You can also see in the picture that it is one piece (one continuous fin) and not two fins stacked on top of one another.

Andrew - thanks for the formula for the calculation.

Thanks

Brad White_125

Not 12.5%

That is too thin a margin in my experience, not sure why it was cataloged so low. A 30% boost (or 130% of one element) is what I have commonly seen. Some manufacturers give it higher but I am skeptical.

I think some of it depends on how it is piped. If in series that is one way, with the temperature decaying along the entire length (fed from the same end). If in parallel, both elements get their full temperature so you would get more output in general. Interestingly this last setup would heat the first incoming air more, hence diminish the upper tier more.... I will have to think about that more.

Brad White_125

Double Fins

Jim- that is a new one on me but I would suspect the performance would be similar to two tiers stacked, just that the fins are connected. I missed that it was one fin. I bet if laid sideways like a convector it would work even better, two elements effectively at 100% output.

Jed_2

Ya!

That's what I said. Thought you would have picked up on that, Brad.

Jed

ALH_4

Ratings

It seems to me that it's all pretty approximate when applying another baseboard rating to this particular situation. The fin thickness,tube diameter, fin spacing, bonding method and area, air flow path through the enclosure, air temperature, flow rate, elevation, etc. all will affect the actual output. Aren't all fin-tube baseboards convectors?

The Argo numbers might be low based on the series piping relationship, but new baseboard compared to this old baseboard will probably cancel out the advantage the parallel piping arrangement might give this setup.

-Andrew

Brad White_126

Sorry Jed

I was reading top-down... you got it first. Great minds, dude!

Jim_65

Thank

you to everyone for their valued responses.

I appreciate it as always!

Jim French