Wrong pump?Heat exchanger sizing

[Deleted User]

but the run with the highest pressure drop, which could be right next to the boiler.

Re-calculate your pressure drop through each branch using that branches required flow. Remeber that feet of head number and find that branch circuit with the HIGHEST pressure drop. To this, add the pressure drop of the distribution/generation system. This is the approximate feet of head required for your system. The flow, if properly calculated, would be be the net out of the boiler divided by 10K. As a quick ROT (rule of thumb) check, take the net out of the boiler, and divide it by the square footage of the home. If the btu/sq foot looks reasonable for your application, then stick with that flow rate. But if it looks real whacky, way out there, then adjust downward accordingly. The ONLY way to know for sure is to do a heat loss calc on it, and that's just a finely tuned SWAG (scientific wild **** guess).

Go to bell and gossett's web site and down load the SystemSyzer soft ware to calculate the pressure drop for the given examples.

Also, FWIW, I've only seen an actual 20 degree delta T on one base board system. ANd that was the first time it had fired, and it was COLD in the new house. All others are significantly less than 20 degrees, like 7 to 10...

Everything you are doing is based on worst case scenario, which in my part of the country acounts for about 2% of the time the heating system is needed.

It is also important to include the EDL (equivelant developed length) of all the fittings and valves in the circuit, or you can do like a lot of engineers and add 1/2 again as much head as you saw in actual pipe length. Personally, I think it is ALL still over kill, but as a licensed contractor, I MUST perform due dilligence in my actions, or it WILL come back to bite me later. And to be quite frank with you, I already have ENOUGH chewing sensations on my back side.

Soon, we will have the ability to not only modulate the flame on our heat source, but I forsee the possibility of having a head reset program based on real time demand and needs. I've actualy done it myself using some off shelf technology and it works quite well. We just have to think outside of the boxes we've been given to install... Roll your own if you have to. The technology is here today.

Wilo, Grundfos, Taco, next...

Kele makes some excellent pressure transducers.

What do you need the HXer for? They're sized based on demand and availability, driven by temperature differential and differential flow.


Proceed with caution...


ME

Jim Austin

Installing new boiler and first think pump size is wrong.
Second would like to add Flat Plate heat exchanger but having trouble figuring out sizing.
At present I have a B&G series 100 supplying three zones.
1)Zone 1:Has 147ft. of pipe with 18ft. of it being 1" the remainder being 3/4" with 15,000 b.t.u. of baseboard.
2)Zone 2:Has 143ft. of pipe with 8ft. of 1" pipe the remainder being 3/4" with 23,000 b.t.u. of baseboard.
3)Zone 3:Has a tee in it serving two areas,one has 125ft. in which 35ft. is 1" the rest is 3/4" with 20,000 b.t.u. of baseboard, the other area has 155ft. and again 35ft. is 1" the rest 3/4" with 30,000 b.t.u. of baseboard.
From what I can figure out I take the longest run to figure out pump head 9.32 ft.???
My boiler has a IBR of 100,000=10 gpm.???
The series 100 only produces 8ft. of head.
I'm guessing I should switch to a Grundfos UPS15-58.
Does this sound right?
The other question I have is how do I determine from the heat exchanger charts what b.t.u. capacity I need?
Is it based on my boiler output,the size of the storage tank,amount of water used?
I plan on installing a 70 gallon storage tank supplying two bathrooms,washing machine,dishwasher.
Any help would be appreciated!
Jim

hr

Is the FP HX

to generate your DHW? If so you may want to prioritize that load. Then you could size that HX and pumps to the full output of the boiler for quick DHW recovery.

hot rod

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