Mixed Emitters off a Mod Con - system design?

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Maine Way

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With tremendous help from this forum (special thanks to Dana), I've managed to evolve my ideas of a new heating system to a single Mod Con and an indirect hot water heater. This is the first post I have made on this topic, so my concept is poorly formed at present.

I have installed PEX under cement board and will tile 30% of the house (mostly downstairs, some up). For the remainder, I am installing cast iron baseboard (sized for adequate heating at 135 deg water). There is also fished basement planned which will utilize radiant floor in a poured slab on rigid foam, but I leave this out of the discussion for now.

I have divided the system into a number of zones for two reasons. Because I am using mixed emitters I need different supply temperatures. Secondly, the future plan is to divide the house into two living units, each with upstairs and downstairs - so they require separate control.

Downstairs will have three zones. One for the radiant in the open concept kitchen/dining and includes bathroom and butler pantry. One zone will be for cast iron baseboard in double living room. One zone will be radiant for a small zone for the entry foyer with double height stair hall. The area can be closed off with doors and could be kept at 50 most of the winter.

Upstairs will have three or four zones.

Off the east stair one zone will be radiant for the walk-in closet and bathroom. One zone will have cast iron baseboard for the bedroom.

Off the west stair, probably combine both bedrooms and both bathrooms with cast iron baseboard on one zone and add a TVR to bed/bath with not thermostat. Or, put the bedrooms on separate zones.

I will need a zone for the indirect hot water tank too.

The boiler I am buying is Lochinvar 89000 BTU Output Knight High Efficiency Boiler w/ Fire Tube Heat Exchanger (Wall Mount) (NG). I felt these features relevant:
1. Three Boiler Setpoint Temperature InputsPlus Domestic Hot Water Prioritization.
2. Four Pump Control System Pump with Parameter for Continuous Operation Boiler Pump with Variable Speed Control Domestic Hot Water Pump Domestic Hot Water Recirculation

So, what is the key strategy to the setup here?

I was thinking of using Cross manifolds. I could use one for radiant and one for cast iron, and work with 2 temperatures? This way my zoning can work off the manifolds. Does this mean I don't need P/S piping? Also, I would need to tee-off the hot water coil zone before I mix down for the space heat? Or, would I not need to mix down because the 10:1 turndown ratio can send the right temp water to begin with?

This boiler has two one inch supplies and two returns (top set and bottom).

Related to radiant heat, the large kitchen zone has 3 homerunned sections, which I plan to run as one zone. Would it make more sense to tee them all into on 3/4" pipe to attach to the manifold instead of taking three spots (since they are all controlled by one thermostat)?

Should I add a floor sensor to the radiant on top of thermostats for room temp? It seems many do both.

I am certainly in a learning phase here for this system. I did install a used Peerless CI Propane boiler with 13 zones for another building. It has worked well for 8 years. But, I am approaching this project with more care and added complexity.

Shawn
 

Maine Way

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There are several ways to have mix water temps. Heres one way a injector system by taco. Download install instructions go to page 7 , drawing 3/705-2

https://www.supplyhouse.com/Taco-PC...MI1faJ34HF8gIVj25vBB3AmQoZEAQYBSABEgKCbfD_BwE
This is a great resource! Thank you fitter30.

Following questions:

1.Can I use a cross manifold with the matching cross controller with the Taco PC705? Or, must I use the Taco Zone Control?

2.The diagram appears to show one zone with unmixed boiler temperature water (DHW and Cast Iron (in my case), and one that is mixed down with return water, presumably radiant floor zones. In my case, I would want DHW to be unmixed (as hot as possible) for quick recovery. And the cast iron to be mixed down to a temperature that would return at below 130 degrees. This diagram still works or would require water temp to be mixed down for the CI space heat as well?

3.This digram shows a circulator for every zone plus an injection pump plus a boiler pump. Would all of these be required to create an efficient system with many zones and different supply temps? Maybe related to question 1, which is a system with zone valves...

Thanks! S
 

Fitter30

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There are several control manufacturers and different ways to pipe a two temperature system. If you decide to use a mix of different brands of controls who are you going to call for any help because tech people from one manufacturer won't touch anothers controls. No you don't need all though pumps for each individual zones just has to be piped correctly. With a priority zone control when dhw call for heat all other zones turn off.
 

John Gayewski

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I think you need to draw a simplified schematic showing what you want to do and people can streamline and brainstorm from there.
 

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I think you need to draw a simplified schematic showing what you want to do and people can streamline and brainstorm from there.
Hello John. That makes sense! I've sketched up something to start with - and am considering the evolution will be a process..
 

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Fitter30

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All loops piped back to back tees. All heat emitters piped reverse return. Both hi and low temp factory made manifolds with shut off valves and flow valves. And what is tvr? For your two story vestibule 50*everytime a interior door is open warn air from the space will rush in to the cold space and cold to space. Insulation doesn't stop the cold it only slows it down thoughs walls will be cold to the interior.
 

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Maine Way

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There are several control manufacturers and different ways to pipe a two temperature system. If you decide to use a mix of different brands of controls who are you going to call for any help because tech people from one manufacturer won't touch anothers controls. No you don't need all though pumps for each individual zones just has to be piped correctly. With a priority zone control when dhw call for heat all other zones turn off.
All loops piped back to back tees. All heat emitters piped reverse return. Both hi and low temp factory made manifolds with shut off valves and flow valves. And what is tvr? For your two story vestibule 50*everytime a interior door is open warn air from the space will rush in to the cold space and cold to space. Insulation doesn't stop the cold it only slows it down thoughs walls will be cold to the interior.
Hello fitter30,

It looks like there is more information in the drawing you sent than I could glean from it...at 72 DPI, I enhanced the resolution but still struggled to read any of the writing. I revised my drawing the best I could tell to match.

I did not understand your question "what is TVR?" - is it a term I used? Maybe I meant TRV for thermostatic radiator valve. Regarding two story vestibule, I see your point. Those doors will be used and may not be a good idea to keep it too cool there..

One of the questions I had about the evolving design, is if the cast iron radiators should be after the injector, since they would work better with cooler return for condensing (but not ass cool as floors). So, the DHW and the single radiator, which is used only when in the breakfast nook on cold days, would be the only loops using full temp boiler water?

Also, I have seen radiant floors use both floor and room thermostats to control one zone. Does thus have an important advantage?

Thanks!

Shawn
 

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Fitter30

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Hello fitter30,

It looks like there is more information in the drawing you sent than I could glean from it...at 72 DPI, I enhanced the resolution but still struggled to read any of the writing. I revised my drawing the best I could tell to match.

I did not understand your question "what is TVR?" - is it a term I used? Maybe I meant TRV for thermostatic radiator valve. Regarding two story vestibule, I see your point. Those doors will be used and may not be a good idea to keep it too cool there..

One of the questions I had about the evolving design, is if the cast iron radiators should be after the injector, since they would work better with cooler return for condensing (but not ass cool as floors). So, the DHW and the single radiator, which is used only when in the breakfast nook on cold days, would be the only loops using full temp boiler water?

Also, I have seen radiant floors use both floor and room thermostats to control one zone. Does thus have an important advantage?

Thanks!

Shawn
Connections to the injection pump loop from boiler and radiant piping back to back tees. Bottom line on drawing from injection pump loop to boiler - air separator, expansion tank and fill. They make manifolds that come plumbed
with shut off valves and flow control valves in pex and copper for zone piping. All zone piping piped reverse return ( first in last out). Taco make a E series pumps that use ecm motors very efficient.
 
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