# Thread: Help we are freezing our as*s off.

1. ## Help we are freezing our as*s off.

Two Slant fin 300000 BTU boilers in 15000 sq ft condo complex. Approx heat load of 360000 BTU. 2 " main loop. All feed with 1" copper. Xtank shoved behind boiler with no way to change. Sticker said "Proudly installed by Dun-rite Plumbing & Heating". Had all I could do to keep from throwing up. It was 3 degrees this morning. Necked a 2" circ pump down to 1" 60' away. You should hear the velocity noise. Could not get the building over 53 degrees. They got what they paid for. The HOA don't understand "But we just put them in last year" There really is no cure for stupid.

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so what did you do to fix it?

3. ## Nothing yet

Originally Posted by blitz
so what did you do to fix it?
Nothing yet praying for warmer weather. HOA has to make some decisions.

4. So what's the biggest problem here...the undersized equipment or the piping/distance?

Non-boiler person here - looks shiny and new enough to work

5. Originally Posted by hurtinhvac
So what's the biggest problem here...the undersized equipment or the piping/distance?

Non-boiler person here - looks shiny and new enough to work
i would have to say the 1" pipe. the boilers should have atleasy kept the [lace a little warmer. probably not at t-stat satisfaction.

6. ## Piping Calculatons

Quick Calculations for Hydronic Heating Systems
Maximum Flow Rates for Closed System, Hydronic Heating
Copper GPM Iron Pipe GPM
½" 1.5 ½" 2
¾" 4 ¾" 4
1" 8 1" 8
1 ¼" 14 1 ¼" 16
1 ½" 22 1 ½" 24
2" 44 2" 48

Flow rate calculations @ 20 degrees F drop = 1 GPM for each 10,000 BTUH
What does the above mean? Assume you have a 300,000 BTUH load on a closed hydronic system with two zones. First zone is 130,000 BTUH, and the second is a 170, 000 BTUH. You can determine from the Flow rate calculation that you will need 13 GPM for the first zone and 17 GPM for the second zone. Based on the flow capacity in the pipe sizing chart, you can determine that you will need a 2” copper or iron pipe connected to the boiler with a manifold to 1 ?” copper/ iron pipe for zone one, and 1 ?” for zone two.
IE: 300,000 BTUH (Total system) = 30 GPM = 2” copper/iron pipe required
10,000 BTUH
130,000 BTUH (zone 1) = 13 GPM = 1 ?” copper/iron pipe required
10,000 BTUH
170,000 BTUH (zone 2) = 17 GPM = 1 ?” copper/iron pipe required
10,000 BTUH

**Note: These calculations work well on normal residential system piping. The above do not take into consideration excessive piping restrictions and/or excessive friction losses due to unusual/long piping lengths. Exceptional system piping must be determined using piping loss/flow calculations.

7. Originally Posted by Chauncey
Quick Calculations for Hydronic Heating Systems
Maximum Flow Rates for Closed System, Hydronic Heating
Copper GPM Iron Pipe GPM
&#189;" 1.5 &#189;" 2
&#190;" 4 &#190;" 4
1" 8 1" 8
1 &#188;" 14 1 &#188;" 16
1 &#189;" 22 1 &#189;" 24
2" 44 2" 48

Flow rate calculations @ 20 degrees F drop = 1 GPM for each 10,000 BTUH
What does the above mean? Assume you have a 300,000 BTUH load on a closed hydronic system with two zones. First zone is 130,000 BTUH, and the second is a 170, 000 BTUH. You can determine from the Flow rate calculation that you will need 13 GPM for the first zone and 17 GPM for the second zone. Based on the flow capacity in the pipe sizing chart, you can determine that you will need a 2” copper or iron pipe connected to the boiler with a manifold to 1 ?” copper/ iron pipe for zone one, and 1 ?” for zone two.
IE: 300,000 BTUH (Total system) = 30 GPM = 2” copper/iron pipe required
10,000 BTUH
130,000 BTUH (zone 1) = 13 GPM = 1 ?” copper/iron pipe required
10,000 BTUH
170,000 BTUH (zone 2) = 17 GPM = 1 ?” copper/iron pipe required
10,000 BTUH

**Note: These calculations work well on normal residential system piping. The above do not take into consideration excessive piping restrictions and/or excessive friction losses due to unusual/long piping lengths. Exceptional system piping must be determined using piping loss/flow calculations.
Thanks this is going straight into my saved notes

8. Originally Posted by Chauncey
Quick Calculations for Hydronic Heating Systems
Maximum Flow Rates for Closed System, Hydronic Heating
Copper GPM Iron Pipe GPM
½" 1.5 ½" 2
¾" 4 ¾" 4
1" 8 1" 8
1 ¼" 14 1 ¼" 16
1 ½" 22 1 ½" 24
2" 44 2" 48

Flow rate calculations @ 20 degrees F drop = 1 GPM for each 10,000 BTUH
What does the above mean? Assume you have a 300,000 BTUH load on a closed hydronic system with two zones. First zone is 130,000 BTUH, and the second is a 170, 000 BTUH. You can determine from the Flow rate calculation that you will need 13 GPM for the first zone and 17 GPM for the second zone. Based on the flow capacity in the pipe sizing chart, you can determine that you will need a 2” copper or iron pipe connected to the boiler with a manifold to 1 ?” copper/ iron pipe for zone one, and 1 ?” for zone two.
IE: 300,000 BTUH (Total system) = 30 GPM = 2” copper/iron pipe required
10,000 BTUH
130,000 BTUH (zone 1) = 13 GPM = 1 1/4 ” copper/iron pipe required
10,000 BTUH
170,000 BTUH (zone 2) = 17 GPM = 1 1/2” copper/iron pipe required
10,000 BTUH

**Note: These calculations work well on normal residential system piping. The above do not take into consideration excessive piping restrictions and/or excessive friction losses due to unusual/long piping lengths. Exceptional system piping must be determined using piping loss/flow calculations.
added red fractions because I think this was a test or typo.

9. *Note: These calculations work well on normal residential system piping. The above do not take into consideration excessive piping restrictions and/or excessive friction losses due to unusual/long piping lengths. Exceptional system piping must be determined using piping loss/flow calculations.

That being said... without calculation of vertical rises, lengths...and friction losses.... You would most likely have to go even higher than that...

Reminds me when I installed my sprinkler system.... the neighbor hired a "Professional" to install his and has hardly any flow to the heads in the front of the house.... (our houses and lots are almost identical) I did some research and sized the piping accordingly... for correct GPM... length and friction loss etc...and used only a 1 1/2 hp pump and have excellent flow throughout all 3 zones.... He has a 2 hp pump and has very poor flow and has blown 2 seals on the pump already and is beside himself.....waters the grass by hand.....

All I can remember when I was installing my system while his "professional" was installing his....was his "professional" saying I was over-killing on the size of the piping and that it wasn't necessary....

10. I got a better one; 27 unit apartment building largest zone with the most heat loss contains 23 feet of 3/4 inch fin tube baseboard, water temperature of 180 degrees. Now let's do some calculating here, 23 feet at approximately 600 btu per foot of heat output (probably less as probably the fins are bent up and dirty on all apartments. Either way say 13,800 btu per apartment as worst case scenario (although checked one other middle floor unit had 16 feet).
13,800 x 27 units =372,600 btu add a very safe fudge factor of 30% piping loss 484,380 btu.

Guess what size boiler I found in the mechanical room? How about 2.5 million boiler with a gas oil powerflame burner! With a 24 inch flue. My brother and I are still looking for the rest of the building this thing must be hooked to, but since the place is a stand alone and originally a hotel in the 1920's this is all there is.

Did I mention the supply line is 3 inch copper and the return is 2.5 inch copper? I told the customer we are going to save him at least 100% of his monthly heating bill. I think I might even guarantee this in writing.

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