gravity hot water

bob e.

Just sold an ultra 210 for an old hot water gravity system, also a taco delta T

for system circ. do you see any problems?

thank you

Jean-David Beyer

Are you going to pipe it exactly as in the boiler manual?

Note: I am not a professional.



The boiler must have at least the minimum required flow rate through the heat exchanger. So normally this would be piped primary-secondary with a Taco 0014 and a FloCheck valve in the primary loop. I do not see a model 210 in my manual; only 80 and 105 that take a Taco 007, and 155, 230, and 310 that take the 0014. I will assume a typo and that you are using a 310.



For that you will want the primary loop to be piped with 1 1/2" pipe.

Are you using the Taco delta T for a circulator in the secondary loop? It is just a quibble, but if you use a circulator there, is it still a gravity system? If the secondary part of the system has zone valves, the right size deltaT circulator might be a good design.



I hope you did a heat loss calculation to size the boiler. A 310 is pretty big (310K BTU/hr input) and the modulating aspect of the boiler will be useless if it is too big. Since my small Cape Cod house calculates out to need about 30K to 40K I infer this one is almost 10x larger or lossier than mine. Could be, I suppose.

bob e.

gravity hot water

JD

thank you for you thoughts.

yes I did a heat loss and counted the sq. foot of the standing c.i. radiators.

I'am using a califi hydrolic separator on secondary side with the taco variable speed pump. single zone one stat. ultra 230.

my plan is to set delta t @ 20 deg and fine tune if required.

what do you think?

thank you

Jean-David Beyer

I think you should ask a professional.

That must be a big house compared to mine to require so much heat. Of course, my house is small (750 sq.ft. downstairs, 450 sq.ft.upstairs). Or maybe you are someplace much colder than I am here in New Jersey.



If the "califi hydrolic separator" is something like this:



[url=http://www.caleffi.us/caleffi/en_US/Site/Products/Product_news/args/detail/~Details~News~news_detail_0000144/type/newshome/index.sdo]http://www.caleffi.us/caleffi/en_US/Site/Products/Product_news/args/detail/~Details~News~news_detail_0000144/type/newshome/index.sdo



it should work fine as a replacement for the closely separated Ts in s primary-secondary system. It even has the advantage of dirt removal and a small automatic air vent and, depending on circumstances, be easier to install. I think of it as being on the border between the primary and secondary side. On the other hand, I think a more efficient air extractor, such as the small Taco 4900 series or the appropriate size Spirovent would be desired to get rid of the dissolved air and microbubbles. How important this is in practice I do not know, but the vendors of these products think highly of them.



I do not fully understand why one would wish to control the heat loss through the heat emitters. For a condensing boiler, I can understand wanting as much loss as possible through them so as to get the lowest possible return temperature to the boiler. On the other hand, if you are feeding a lot of finned tube baseboard heating in a series circuit, it would mean that those baseboards at the cool end might have to be quite large, so a higher flow rate would reduce the end-to-end temperature differences. (I am assuming no one is advocating flow rates over 4 feet per second.) I assume a professional could address such an issue. That deltaT circulator seems to be adjustable over a wide range (5F to 50F) so you should be able to make it do whatever is best once you find out what is best.