Boiler Schematic for Comment

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Maine Way

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Hello All,

I plan to use mixing valves as opposed to injection to mix temperatures for radiant heat.

The boiler I have chosen has a number of sensors and features which regulate water temperature in order to maximize condensation. Above this requirement, my system also needs to control water temperature for radiant floors. Most of my confusion revolves around how added sensors and controls will play with the existing ones on the boiler.

I’ve attached a file of the schematic I’ve developed to this point.

1. Lochenvar Knight has an outside reset and regulates water temperature, system pump, turndown ratio (10:1) in order to achieve condensation. And it has DHW priority zoning option. Would these controls be adequate to supply domestic hot water and CI baseboard zones? I don’t need any additional mixing to adjust water temperature for cast iron space heating?

2. For the radiant floor zones I plan to use a taco 1", 3 Way Setpoint I-Series Mixing Valve w/ Sensor or similar. I don’t need any extra controllers with this valve? There is also a valve available that has an outside sensor. Is this important for the system? The boiler already has that and my assumption is that the boiler is tasked with monitoring and adjusting water temperature to maximize efficiency (as cool as possible) and the mixing valve provides a constant, low temperature for the radiant floor. Will the boiler system get confused by the fact that some of the water in the system is mixed with return water sometimes? Or, since the boiler measures supply temp and outside temp and perhaps the length of the fire cycle to satisfy the thermostat, it does not care what happens on the return loop?
 

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  • boiler schem 4.pdf
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Fitter30

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Only thing I'd change amtrol tank piping. The two pumps would fight each other. Feed tank with back to back tees on the supply line from boiler and turn pump around with flow to tank. What zone controller are u using, number of thermostats. Any condensing boiler is only 95% if return is 130* or under above 86%.
 

John Gayewski

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1. No your good
2. Make sure your turndown pump won't pump below the minimum requirement for the mixing valve. Mixing valves have a minimum and maximum gpm required to operate.

The drawing. This is not a primary secondary schematic. Primary loop is just that a loop from the boiler to the boiler. The pumps need to pull off of that loop wit closely spaced tees, and return to it. A condensing boiler likes cold return water. Your short cycling your primary loop with the tees you have drawn. Your boiler will just get wasted from itself and the loops will cycle with themselves. You're basically just spinning in place with nowhere for hot water to get in.
 
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Maine Way

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Hello fitter30.

Thank you for the reply.

I've modified the schematic based on your comment.

I also included the drawing I referenced. I've simplified the layout with one circulator for high heat and one for the radiant heat, which will have a controlled, low temperature for that manifold. To me it made more sense to split the system into two manifolds and then zone the branches, since zones are small.

I was planning on a thermostat for all areas described in the drawing. There would be eight total. Each branch of the manifold would have an actuated valve controlled by a thermostat. And, the controller would also run the pump for that manifold. I was thinking I would get a TACO controller of some type - suggestions?

The boiler itself has DHW priority and could run the DHW zone and the system pump? I'm still not sure how the wiring would work to divide the work between the controller box and the boiler computer.

My theory in terms of the water temperature return is that the cast iron baseboard temperature is controlled by the boiler. The boiler seeks to use low temp water to achieve condensation, and provides for these zone lowest temp possible to do the job based on outside sensor and thermostat. For the radiant heat manifold, the 3-way valve will provide low temp water to these zones, which will achieve condensation. For the Amtrol, I assume the boiler will probably;y use high heat for fast recovery, and it won't achieve condensation for this function.

Shawn
 

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  • boiler schem 5.pdf
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  • LOCH SHCEME.pdf
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Maine Way

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Hello John,

Thank you for the reply.

I've posted in my reply to fitter30 two files. One of a revised scheme and one of the drawing I referenced.

I have identified in the new schematic the closely spaced tees for the DHW and for the initial loop to and from the boiler. Should I have more these in the system supply and return of the zone manifolds?

Based on the manufacturer drawing, have I misinterpreted how I should lay out the piping?

Thank you,

Shawn
 

John Gayewski

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Hello John,

Thank you for the reply.

I've posted in my reply to fitter30 two files. One of a revised scheme and one of the drawing I referenced.

I have identified in the new schematic the closely spaced tees for the DHW and for the initial loop to and from the boiler. Should I have more these in the system supply and return of the zone manifolds?

Based on the manufacturer drawing, have I misinterpreted how I should lay out the piping?

Thank you,

Shawn
Do you have a three way diverter or a three way mixing valve?

Lock has a modified "moosehead" setup in their schematic. You have a loop in the middle with no circulator on it. Plus the tees are not setup correctly, but I see you've changed that.

It's possible I've interpreted your drawing incorrectly. Primary secondary has evolved quite a bit since I became familiar with it. There are some drawings I look at that don't make a whole lot of sense to me, but the manufacturer says they work, and they seem too. It used to be toy wouldn't connect the supply and return with a mod con, then they changed that. Most of my study with this is based on cast iron boilers, mod con boilers area so flexible that they sometimes boggle my mind.

I think I would setup the radiant zone to take return water from the high temp zone.
 
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Maine Way

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Thank you John!

I am definitely learning here. So the comments are useful. It seems to me that standard approaches are always changing. I put in a cast iron boiler years ago, and the circulator on the return or supply side seemed to be an issue of debate. Anyway, I will update some photos once I have some dry fitting done. Maybe comments then will be easier to manage with a clear direction.
 
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