Replace B&G 100 or use Taco 007 monoflo
Comments
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Monoflow tees are very restrictive. Note that a 1 1/4 monoflow tee has a Cv of 24, but that is with the side branch plugged. With a flow of 11 gpm (reasonable for 1 1/4") and a Cv of 24 that is about .5 feet of head and that is just 1 tee. With 9 tees which I had in my house that could be 4.5 feet depending on the flow.
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The branches were 1/2" but that didn't benefit it much. This setup was completely stupid. And it was CI radiation to boot. Interestingly enough, they piped the second floor in 1".
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Drop the pressure and pray you don't have to drain down the whole system and bleed EVERY radiator.
Those prayers never worked for me on CI. They never had any ball valves or bleed valves anywhere in the boiler room. Just used the bleeders on the CI. Worked fine until you had to change someting……………
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Yes, it is a simple answer for those who refuse to read.
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Hvacnut,
Your customers are lucky for your after normal working hours service.
I learned to look at the repair challenges encountered as the homeowners issues, not mine, and, an opportunity to up sell improvements for ease of future service.
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sorry i read it but didnt really understand it all. not blessed like some people to know everything
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Pfffft………………try working with a system that has six 3/4" Tees, each with a Cv of 4.2. Never could get 4 GPM out of it even with a Taco 11!!
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I was called into a job years ago where my brother in laws father (in his 90s) was complaining that his addition on his house was cold. He had an old gas fired steam boiler with a tankless heater that heated the HW loop for the addition. There were 2 or three CI rads and they had piped a split loop 1" supply and 2 3/4 returns. (way overkill) He already had every local plumber look at this with no luck. They had monkeyed with this for years. They had taken the CI radiators out, put baseboard in and then put the CI radiators back in. I don't think it ever worked right. I think as his father got older he couldn't tolerate the lack of heat.
It had a Taco 110 circ.
After staring at this for a while feeling the pipes and bleeding the system I stood there looking at the tankless coil with it's 1/2" connections and pictured how much 1/2" tubing it took to make the tankless coil.
I upped the pump (forget what I put in) and it was fine.
I never missed when sizing a pump for a new job but going to an existing job that sort of works it gets in your head.
You have to step back , start from scratch gather some information and figure it out.
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it would be fairly easy to just plot the B&G curve on the Taco graph
Better yet, plot the system curve and lay it over the pump curve to find the OP, operating point
The pump curve is only 1/2 of the story
This example from Idronics 16 shows how a steep curve and flat curve pump can hit the same OP, as @LRCCBJ mentioned A few times😯
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
if only someone made a slide rule for this….
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I have a French curve left over from high school drafting class. It works well to connect the dots that you plot.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
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This was back when full service meant full service. Clients were covered for all repairs. And the oil department still made a killing.
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