Advice on Fine-Tuning Primary/Secondary Pumps

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fitter30

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Change the mass setting to high mass radiate from cast iron radiators. Own a clamp on amp meter? Any lite guage wire can make amperage muiltiplier to get a accurate amp reading for the heat anticipator in each thermostat. Just remove thermostat to subbase jump r-w with multiplier measure amperage reset anticipator. Video for making a muiltiplier.
 

davie

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That's why separating the emitter types can help you when you build a system.

If I separated the rads from the floors, what would you then change? Send hotter water to the rads?

Mixing emitters in a loop doesn't give uppity much control.

Just to clarify, when you say "loop," do you mean in series? The emitters are all in parallel within the zones.
 
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John Gayewski

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If I separated the rads from the floors, what would you then change? Send hotter water to the rads?
You then have different temperatures to work with. Right now, with what your trying to do, there is one temp. The only way you can adjust anything would be to adjust the gpm, but your extremely limited because the boiler has a minimum. But with different return temps you can actually grip the wheel and steer it.

I personally don't see the issue your having. I don't know why you want the primary and secondary zones to match. You'd have to add components to separate them, and if you're happy enough right now, I don't think the juice is worth the squeeze. I'm just explaining how you could achieve it if you feel the need.
 

davie

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You then have different temperatures to work with. Right now, with what your trying to do, there is one temp. The only way you can adjust anything would be to adjust the gpm, but your extremely limited because the boiler has a minimum. But with different return temps you can actually grip the wheel and steer it.
That makes complete sense.
Idon't know why toy wasn't the primary and secondary zones to match.
Looks like an autocorrect error here, but I can't make sense of it.
 

davie

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I don't know why you want the primary and secondary zones to match.
It's not that the zones don't match. The temperature difference I'm fretting about (maybe unnecessarily) is across the hydraulic separation —i.e. closely spaced tees— between boiler pump and zone pump.

From my observations it seems a good portion of the hot water supply coming from the boiler isn't getting out into the house. It is just going straight back to the boiler return.

In this picture, the upper grundfoss pump is on the primary loop to and from the boiler return and supply. The green taco pump at the bottom is pumping out to the house and that water returns to the closely spaced tees.
IMG_20211117_150130-overlay.jpg


And here, in a close up, is the specific issue that I'm having. The water being sent out to the house is often no hotter than the return on the primary loop.
prim-sec-temp.jpg


(In this example there is a drop between 90F and 88F. But often there is no difference.)

What I wonder is whether all of the water heading into those closely spaced tees is mixing, and then half is going to the return and half is going to the house.
 

John Gayewski

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It's not that the zones don't match. The temperature difference I'm fretting about (maybe unnecessarily) is across the hydraulic separation —i.e. closely spaced tees— between boiler pump and zone pump.

From my observations it seems a good portion of the hot water supply coming from the boiler isn't getting out into the house. It is just going straight back to the boiler return.

In this picture, the upper grundfoss pump is on the primary loop to and from the boiler return and supply. The green taco pump at the bottom is pumping out to the house and that water returns to the closely spaced tees.View attachment 78873

And here, in a close up, is the specific issue that I'm having. The water being sent out to the house is often no hotter than the return on the primary loop.View attachment 78874

(In this example there is a drop between 90F and 88F. But often there is no difference.)

What I wonder is whether all of the water heading into those closely spaced tees is mixing, and then half is going to the return and half is going to the house.
Right I've understood your issue from the start. Thr primary zone and the secondary zone doesn't match up in your view which is going to be normal. Make no mistake these are independent zones. If your boiler wasn't getting the hot water out into the heating zones you would be short cycling. You could perhaps get longer run times if you separated your flooring from your rads as we have established.

This is something you have to decide for yourself if it's worth. You'd get longer run times. Is the difference in cost between running 15 times per day and 10 times per day worth it, being as the amount of time that the boiler runs in total wouldn't change? That's up to you.
 

davie

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Is the difference in cost between running 15 times per day and 10 times per day worth it, being as the amount of time that the boiler runs in total wouldn't change?
Thanks again for your advice.

I think the easy answer is no. Your point about the total boiler running time is well noted.
 

fitter30

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Primary/ secondary loop with closely placed tees. Boiler pump moving 20 gpm secondary pump 8 gpm 12 gpm returns from primary 8 from secondary. Boilers like to run and not cycle for the highest efficiency. Did you change the mass setting? Raise the differential setting to 25:30*f
 
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greenmountain

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Would a buffer tank or hydraulic separator help with his scenario?
Maybe not worth the investment in parts and all the labor to change that...

As a relatively easy solution, would trading the tee's out for directional/diverter tee's to bias the flow from primary supply into the secondary supply and secondary return into primary return do anything to improve things?
 
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John Gayewski

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Would a buffer tank or hydraulic separator help with his scenario?
Maybe not worth the investment in parts and all the labor to change that...

As a relatively easy solution, would trading the tee's out for directional/diverter tee's to bias the flow from primary supply into the secondary supply and secondary return into primary return do anything to improve things?
That's not what you want as far as the tees. A hydraulic separator is a fancy way of making the zones or loops run separately. It's achieved by closely spaced tees. The hydraulic separator just lets them run even more separately. The improve would be very small.
 

fitter30

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Would a buffer tank or hydraulic separator help with his scenario?
Maybe not worth the investment in parts and all the labor to change that...

As a relatively easy solution, would trading the tee's out for directional/diverter tee's to bias the flow from primary supply into the secondary supply and secondary return into primary return do anything to improve things?
You keep trying reinventing the wheel. Mixing cast radiators with floor heat and thinking about diverter tees in ur secondary loops which they aren't made for. The system seems to be running ok. Primary loop temperature difference will vary with load unless having a outdoor reset and that won't be perfect, just like the secondary load changes. Wrote that it heats the house on the coldest days floors barely warm than room temp. Since floors have more mass than cast iron radiators they take longer to heat. Without separating the cast radiators and floors won't work correctly.
 
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