Calculating head of existing system

Kevin Wyman

Living in a 1936/1960 home with the original coal converted to oil boiler, three pump zones, one to the original gravity hot water cast iron radiators (mostly Sunrad in wall radiators and two cast iron tube radiators on third floor) and two newer copper finned radiation zones I am looking at improving the efficiency of the system. Obviously a new boiler would help but my question today concerns the pump zones. Specifically how should I go about calculating the head loss through the Sunrad radiators (i.e. what is the pressure drop?) and how would one estimate the piping elbows and what not hidden behind my plaster walls?

Should I also plan on replacing the large 3 - 4" mains in the basement? (These are horizontal so I take it this was never a steam system nor any evidence of traps).

My goal is to weather out one more New England winter. The existing pumps seem to be quite large on the 3 story cast iron circuit(s) and the second story addition copper fin. The small 1st copper fin with its Taco circulator runs very hot to the touch but is circulating heat.

Should I replace all three pumping zones with a single pump and zone valves? I am trying to minimize my energy cost including my pumping energy.

Thanks.

Ron Schroeder_2

If you have the curve for the old pumps, you can estimate the flow from measuring the pressure differance between the input side and the output side of the pumps.

Guesses without seeing it would only be guesses. If i was to pull a rabbit ....er.....pump out of my hat, I would use a Grundfos UPS15-58FC since it is 3 speed and one of the speeds would probably work. If you go with Grundfos pumps, make sure that you have enough give in your piping since the Grundfos is 1/8" longer than a Taco.

Changing from multiple pumps to a single pump with zone valves would depend on how much plumbing would need to be changed.

The Taco should run as hot as the water it is pumping.

Steamhead

On a gravity conversion

the old books I have say to assume a head of 3-1/2 feet.

To determine how much pump you need on that old gravity zone, you need to know how much radiation is on it. The Sunrad and tubular radiation is covered in Dan's book "E.D.R.", which you can order on the Books and More page of this site.

Once you know how many square feet of radiation there is, go to

http://www.heatinghelp.com/newsletter.cfm?Id=125

to find out how many gallons per minute you need to pump. Use the chart column for gravity conversions.

Then all you need to do is select a pump that will move that amount or slightly more, at a 3-1/2-foot head. The major pump manufacturers- Bell & Gossett, Taco, Grundfos- have performance charts on their Web sites that you can view or download.

If you need a chart for an older pump, Dan and I both have a bunch of them.

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Kevin Wyman

Existing System Head

I did a little more digging and cleaning of the existing pumps. Two Taco BD-110-1 (at least that is stamped on the side of the casting) and the new circulator is a Taco 007-5F. I will send my kids around counting the sections of the Sunrad and go about diagraming the blooding piping for the takes offs. The old abandoned side arm heater was really giving off a lot of btus yesterday. (with all that old 3 and 4 inch piping mains in the basement and the sidearm heater, its like having a radiant floor heating system on the first floor. No wonder no snow ever stays up against the side of the house...)I think I found the pump curves at Taco although not positive on the BD-110-1.

Kevin Wyman

The boiler

The boiler appears to be a Pierce Eastwood by Pierce Butler and Pierce Manufacturing... no model number although the number 217 is cast into one of the upper doors.

Steamhead

Taco curves & Pierce info

If I remember correctly, the 110 will pump about 30 GPM at 3-1/2 feet of head, and the 007 will pump about 20.

The Pierce Eastwood was a typical square sectional boiler. Measure the length and width of the firebox at the level of the fire door and we can tell you the model number and rating. It may be possible to baffle this boiler to slow the hot flue gases down so they give up more heat to the water, but this is a job for a pro.

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