dump zone size

[penfrydd]

So I'm to the point of needing to put in the dump zone above the boiler. I've got a 140,000 btu solo 40, so it calls for a 14,000 btu dump zone. How many feet of 3/4" slant fin do I need for that.

If I read the charts correctly, I could get by with 10'? Something about 140 btu loss per foot, but that's at a specific temperature and at a specific water flow. The flow here would be by gravity only during an overheat situation.

So my question is; how many feet do I need?

Thanks,

penfrydd

 

[hayrack]

Don't dump into a radiant zone. You must dump into a baseboard, radiator, modine or such. Pick a heat loop in your house or add something where you can dump and the extra heat won't bother. If your boiler is sized and plumbed correctly your dump will rarely be used. Dump zones are a good power out safety with an automag not a zone valve.

 

[penfrydd]

That's what my question is referring to...how many feet of 3/4 baseboard do I need to accommodate 14,000 btu?

penfrydd

 

[dogwood]

Penfrydd, when figuring this out recently I went to the Slantfin site, (broken link removed to http://www.slantfin.com/product-baseline-2000.html) and found out how many BTUs per foot the various model Slantfin baseboard I was considering put out. It was then a matter of multipling out how many feet were needed going by the chart. For my dump zone I ended up with 30 feet of their most common baseboard for a Tarm Solo Innova 50 rated at a max of 172,000 BTUs. Tarm's manual called for a dump zone that would put out 10% of the boliers maximum output which equals in my case 17,200 BTUs. The baseboard purchased puts out 600 btu per foot. I ended up needing 28.6 feet, bought 30 feet, to get an output of a little more than needed and am hoping for the best when installed.

There are some excellent and fairly recent threads on this subject that you could use the search function to locate, that more closely address the vagaries you are concerned about . I'm sure you'd find them helpful. I know I did.

Mike

 

[hayrack]

slantfin is a brand of radiant floor heat, that is why I thought you were dumping in a radiant loop

 

[jebatty]

For my Solo 40 I use fin tube based on 500 btu/ft.

 

[thehaas]

i just installed a d&s wood coal boiler ,iam not aplumber but work on cars so pretty handy.manufacturer told me half of water capacity of boiler,mine holds 75 gallons so made my dump zone around 40 gallons.went on web for infomation reading for hours really could not find any stright answers .my wiring for dump zone is aqastat reads water temp sends signal to taco zone and circulator controller .upon temp rise cotroller turns on circulator and opens zone valve water circulates into old cast iron radiators that hold about 10 gal each then back to boiler.also put another zone valve that is normally closed but apon power lose opens for pwer outage times,ran next to other zone vave .every thing works great would not try making 3/4 baseboard dump zone tryed did not work does not hold enough volume water plus circulates to fast not losing heat before returning to boiler.actually dump zone cant really be made to big because your using it to bring temp down from 200 to 180 in about 15 minutes.one more thing when combining with original system plumb in series so output of original boiler runs up to baseboard comes back dowm into your zone vaves the into your return pipe then into wood boiler return comes out top into original return boiler and back aroung .you must put 3 valves on return line one on return to wood boiler one on wood boiler output line going into original boiler.last one between firt two.when burning wood close middle valve makes water not able to get back to original boiler return path so goes to wood stove boiler then after coming out wood boiler goes through 3rd valve thats open water hits opposite side closed middle vavle that forces water into return pipe original boiler.valve set up i got from install pages alternate heating directions web page.i tryed hooking in parallel like d&s has in there directions did not work well water takes path least resistance so most water flow when my circulator turned on was through original boiler and only little flow through wood boiler,temp in wood boiler wad 200 and in original boiler was 150 so oil fired boiler would kick on upon call for heat.

 

[penfrydd]

Thanks to all who responded. I finally got on the slant fin site and found the answer of about 500-600 btu per foot. Given that amount, and given that I currently don't have heat upstairs, and given that the dump zone should be above the height of the boiler, I'll just make the dump zone the upstairs heat zone and put in the automag valve etc as described in the solo 40 diagrams.

Thanks again.

 

[jebatty]

Good plan. Make sure there isn't a check valve in that zone line somewhere to prevent ghost flows; that would prevent the zone from operating in a power out situation.

 

[Gooserider]

Don't dump into a radiant zone. You must dump into a baseboard, radiator, modine or such. Pick a heat loop in your house or add something where you can dump and the extra heat won't bother. If your boiler is sized and plumbed correctly your dump will rarely be used. Dump zones are a good power out safety with an automag not a zone valve.

It is possible to dump into a radiant zone under some conditions, though it often won't work... The zone has to be set up in such a way that it can gravity flow under power failure conditions, which means very low flow restrictions, which is usually a stopper. Obviously, the zone also needs to be above the boiler. Modines are also not a great idea since they generally rely on electric fans to get the heat out of them, which is obviously an issue in a power failure... Fintube, baseboard, and radiators are all very good dump zones. Storage tanks if plumbed correctly, and in the right relationship to the boiler can also be used as a dump zone.

Gooserider

 

[jebatty]

My overflow loop is on the ceiling, vertical 1" from the boiler to 3/4" Automag and then to the loop itself. The loop is 4 runs of fin-tube, with a manifold, sloped upward, and then a 3/4" manifold/return line sloped downward and then vertical down. In a couple of test runs, the loop starts to heat quickly, although it takes some time for the full loop to be energized. Obvious that some legs are taking hot water before others. But the key thing is that in overheat, the draft fan shuts down, if in high burn the fire slows down fairly quickly, and heat is being dissipated. The draft fan shuts down at about 185-190F, the overheat triggers at 210F, so there is some buffer capacity in the boiler to absorb extra heat as the fire quiets down. Then the loop to take any excess. My test runs have proved that boiler does not blow the relief valve, and in fact really does not rise much above the 210 setting, so I think the risk of pressure rising to 30 psi and the relief valve blowing is remote.

 

[chuck172]

Thanks to all who responded. I finally got on the slant fin site and found the answer of about 500-600 btu per foot. Given that amount, and given that I currently don't have heat upstairs, and given that the dump zone should be above the height of the boiler, I'll just make the dump zone the upstairs heat zone and put in the automag valve etc as described in the solo 40 diagrams.

Thanks again.

That's what I did, easy enough to test when you're done.