Variable Primary Loop

SM

I have attached a drawing of a proposed piping for a pair of 300K boilers that will be going in a church hall/school. Two zones with indoor feeback. Boilers will have outdoor reset.

Questions:
1. What is wrong with this design?
2. Where should the spirovent be placed?
3. Where should I have check valves?
Thanks

Al Letellier_9

variable P/S

this is a new one on me. Never seen it done like this before. Your drawing shows the take off for the zones after the primary pumps. Why two of them? And you show a cross at the zone connections. Why? The spiro vent should go on the primary loop piping right after the boiler secondary connections. I assume you have equal temps in the heating zones and if doing outdoor reset, you'll inject high temp into the zones on domestic call. Check the application book for Tekmar and the piping diagrams are there. I think you have one pump too many in this application. Also the zone supply and return piping need to take off the primary with closely spaced tees, not crosses as you have drawn.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Weezbo

i would move the Indirect. let it see The hottest H2O

first. the injection loops would work buh i think you would want the check in the return from 5 and 6 to allow it a chance to find its own path home. that cross you have might not quite mix unless it was large enough to accommadate the flow of the constant circ system and the injection system at the highest load demand. the injection side of the cross might not have to be as large as the system size is what i am saying...

put the boiler pumps on the return and the spirovent at or near the first 90 in your primary.

i think the pump on your indirect as it is now wont function continually to help the injection bridges mix the water temps . if the pump to One of the injection systems was ahead of both bridges and the bridges had globe valves...thats not great either , buh you would use one less pump and the indirect would be seeing the boiler temnps immediately my scanners broken sorta:(

two closely spaced "T's" is a better idea. the balancing valve i would think to be a necessity.i would check 18" after eack system pump...

SM

Two zones

Both P3 and P5 are variable speed/injection pumps into two different zones with two different temperature in the zones based on zone feed back. We need to run constant circulation becasue the zones have unit ventors with outside air and have potential to freeze up and there is also some base baord in the zones. So if we reset each zone with zone feedback to control the temperature of the water going to the zones we would vary the flow in the primary. I did wonder about the cross vs. closed space tee's. Also my consern about the spirovent is that the velocity could be low at times with in the primary loop with both zones are calling for little or no heat.

SM

If I go with closed spaced tee's

would I need the check in the return of P5&6? Would seem with the constant circulation on the zones water could only go one way.

hr

Why not

use a pair of mod con boilers? This gives you system reset via the boiler control, dhw priority, modulation, sealed combustion, and the highest efficiency.

Really not enough info in your drawing. What type of emitters, what temperature requirements? Did you do a load calc to size the boilers?

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

SM

Heat emitters

The heat emitters are baseboard, fan coil units and unit ventilators. I have a copy of the original drawings and the submittal for the emitters, which were originally, design for 200-degree water with a total load of 1MM BTU load when the building was built in 1966. Since then the roof was replaced and insulation add. The janitor and others have said that made a big difference in the heating of the building. There is no stat in the school to turn the heat on or off. Currently the janitor runs the boiler off the limit control to adjust the temperature in the school. If he feels hot he turns it down. If he is cold he turns it up. He told me that he runs the water between 100-140 degrees if it is supposed to get real cold some times he adjust the limit control to 160 degrees. There is an outdoor stat that he uses to shut the whole system down when the weather is warmer out (50-60). The boiler there now is 1MM btu boiler.
This past winter I installed a data logger on the system. And he is correct in what he says he does. I monitored RWT, SWT, and OAT from Jan 1st thru April. The coldest night I ever saw was 10 degrees (design is 0 degrees) and the boiler was set at 120 degrees. I also notice that even on the coldest night the boiler fired for about 8 minutes and was off for 26 minutes. Never while I was collecting data did I see the SWT above 142 degrees.
So I have not done a heat loss on the building, but from the info I collected with the data logger on the coldest night the boiler ran for 8 minutes and was off 26 minutes and did this repeatedly all night. On mild days it run for 6 minutes and then off for 40 minutes. If I use this data and know that the current boiler 1MM BTU’s 8/34th (8 minutes out of 34 minutes) is 230K BTU’s at 10 degrees out side would have handled the load. So at design temp of 0 degrees 300K should heat the building.
Local supplier has been suggesting that I use two 300K Laars Pennants with 2 stage burner on each. For a total heat output of approximately 512K

SM

Heat emitters

> use a pair of mod con boilers? This gives you

> system reset via the boiler control, dhw

> priority, modulation, sealed combustion, and the

> highest efficiency.

>

> Really not enough info in

> your drawing. What type of emitters, what

> temperature requirements? Did you do a load calc

> to size the boilers?

>

> hot rod

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_



The heat emitters are baseboard, fan coil units and unit ventilators. I have a copy of the original drawings and the submittal for the emitters, which were originally, design for 200-degree water with a total load of 1MM BTU load when the building was built in 1966. Since then the roof was replaced and insulation add. The janitor and others have said that made a big difference in the heating of the building. There is no stat in the school to turn the heat on or off. Currently the janitor runs the boiler off the limit control to adjust the temperature in the school. If he feels hot he turns it down. If he is cold he turns it up. He told me that he runs the water between 100-140 degrees if it is supposed to get real cold some times he adjust the limit control to 160 degrees. There is an outdoor stat that he uses to shut the whole system down when the weather is warmer out (50-60). The boiler there now is 1MM btu boiler.

This past winter I installed a data logger on the system. And he is correct in what he says he does. I monitored RWT, SWT, and OAT from Jan 1st thru April. The coldest night I ever saw was 10 degrees (design is 0 degrees) and the boiler was set at 120 degrees. I also notice that even on the coldest night the boiler fired for about 8 minutes and was off for 26 minutes. Never while I was collecting data did I see the SWT above 142 degrees.

So I have not done a heat loss on the building, but from the info I collected with the data logger on the coldest night the boiler ran for 8 minutes and was off 26 minutes and did this repeatedly all night. On mild days it run for 6 minutes and then off for 40 minutes. If I use this data and know that the current boiler 1MM BTU’s 8/34th (8 minutes out of 34 minutes) is 230K BTU’s at 10 degrees out side would have handled the load. So at design temp of 0 degrees 300K should heat the building.

Local supplier has been suggesting that I use two 300K Laars Pennants with 2 stage burner on each. For a total heat output of approximately 512K

SM

Heat emitters

The heat emitters are baseboard, fan coil units and unit ventilators. I have a copy of the original drawings and the submittal for the emitters, which were originally, design for 200-degree water with a total load of 1MM BTU load when the building was built in 1966. Since then the roof was replaced and insulation add. The janitor and others have said that made a big difference in the heating of the building. There is no stat in the school to turn the heat on or off. Currently the janitor runs the boiler off the limit control to adjust the temperature in the school. If he feels hot he turns it down. If he is cold he turns it up. He told me that he runs the water between 100-140 degrees if it is supposed to get real cold some times he adjust the limit control to 160 degrees. There is an outdoor stat that he uses to shut the whole system down when the weather is warmer out (50-60). The boiler there now is 1MM btu boiler.

This past winter I installed a data logger on the system. And he is correct in what he says he does. I monitored RWT, SWT, and OAT from Jan 1st thru April. The coldest night I ever saw was 10 degrees (design is 0 degrees) and the boiler was set at 120 degrees. I also notice that even on the coldest night the boiler fired for about 8 minutes and was off for 26 minutes. Never while I was collecting data did I see the SWT above 142 degrees.

I have not done a heat loss on the building, but from the info I collected with the data logger on the coldest night the boiler ran for 8 minutes and was off 26 minutes and did this repeatedly all night. On mild days it run for 6 minutes and then off for 40 minutes. If I use this data and know that the current boiler 1MM BTU’s 8/34th (8 minutes out of 34 minutes) is 230K BTU’s at 10 degrees out side would have handled the load. So at design temp of 0 degrees 300K should heat the building.

Local supplier has been suggesting that I use two 300K Laars Pennants with 2 stage burner on each. For a total heat output of approximately 512K

hr

Gosh

that is quite a jump from 1 million to 230K. Why not run a load calc on the building as it actually stands today?

If in fact 230K get's the job done why install 512K? That's twice what you need. Sounds like a pair of 180K, even at 85% efficiency, would cover the load.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"