Adding a radiant zone, how to plumb and and how to wire

RascalOrnery

I'm helping a friend add a radiant zone to his existing hot water baseboard home system. The radiant will be for his 24 x 24 garage. He installed a modine unit but wasn't very impressed with it's performance and suspect part of it could be the piping/wiring of the existing system.

In the first picture the circulator on right feeds his indirect and the one on the left feeds all the zones, the returns are seen in last picture - using zone valves. The supplies aren't really like a manifold but just split outputs from the two pipes shown. Currently the zones are controlled by a bird's nest assortment of wires and relays which I know little nothing about.

He would like to use what was the modine supply as the radiant floor supply and use a mixing valve. We were thinking of replacing all the controls with a single multizone switching relay, but since the zones are on valves (24v?) and the radiant would probably require an additional circulator post mixing valve it seems like it could be a little tricky on how to wire the primary 007e to activate both when a zone valve opens as well as when the radiant zone calls.

So some starter questions:

For a likely 2 loop system would the 007e be inadequate to push through 1/2 pex and a mixing valve (plus any other zones that might be calling)? My understanding is it is always best to pull through a mixing valve, in that case the two working together is it possible the primary circulator (pictured) might cause issues or is that pretty much a moot point as long as the radiant loop dedicated circulator is properly sized?

Are there zone controllers/switching relays that output both for 120V (circs) and 24v (zone valves)? Or is this a case to have a separate controller for the two with end switches tied into the primary circulator? Sorry for the duplicate pictures, things don't seem to cooperate today.

Jamie Hall

You do have to pull through the mixing valve on a setup like this. The cold side comes from the system return, and the hot side would be from the system supply — could be the Modine.

There are any number of ways to wire up a relay to turn things on when you want them on — and off when you want them off. There are some zone controllers with various nifty relays, but it may be easier to figure what you want running or open and just use some relays to accomplish that and isolate the various voltages you need.

GroundUp

A thermostatic mixing valve needs to be pulled through for proper operation- that is not negotiable. You could use a non-thermostatic and potentially get by with what you have there, without changing the wiring, however something like a Taco ZVC406 has provisions for a primary circ as well as a priority circ (which would be the indirect in this case) in addition to <6 zone valves. That's probably the route I would go, short of changing everything out to a thermostatic mixer and adding the circ which would necessitate both a switching relay and a zone valve controller if using modern tech.

RascalOrnery

Thanks, since there is no primary/secondary loop in the case the radiant is the only zone running, would the current 007 circulator be OK pushing through the back of the mixing valve while the zone specific circulator PULLS through the mixing valve? Or would I need to implement a diverter(?) valve going to the return for best results?

hot_rod

You could buy a mixing station that includes the pump, manifold and a small separator built in. Caleffi has a 3 port version, also available as inverted with then ports facing up..

What size is the boiler? That garage load, 12- 15,000 btu/ hr possibly? will pull down the return to the boiler, keep an eye that the boiler doesn't condense for long periods when all zones are calling.

You really want to pull through any mixing valve to get even mixing through the valve.

Is the boiler on ODR? You could try a manual 3 port, let it ride along with the ODR temperature. A motor could be added if you want more accurate control.

Screenshot 2024-08-23 at 6.58.40 AM.png

GroundUp

A 4 way non-thermostatic mixer would utilize the existing circ and would also temper the return water to prevent condensation issues with the boiler, keeping the modifications minimal. If you wanted to switch it to a thermostatic with an extra circ, you'd have to use the existing circ as a "primary loop" of sorts and run the mixed loop off of it.

hot_rod

As @GroundUp mentioned, a 4 way valve give you 2 mixing points. One for radiant, one for boiler protection. It would need an actuator and control to be able to adjust and respond to those temperatures however.

Screenshot 2024-08-23 at 11.11.47 AM.png

Screenshot 2024-08-23 at 11.11.33 AM.png

HomerJSmith

@hot_rod @Groundup , I recently remove one of those Tekmar's 4 ways and the original installers put a sensor on the radiant but forgot to put a sensor on the boiler side. The rust and erosion on the boiler was so bad that the boiler went to the dump and the boiler pump impeller was so clogged up that it wouldn't pass water. The only thing holding that boiler together was hope and a prayer.

GroundUp

https://forum.heatinghelp.com/discussion/comment/1808676#Comment_1808676

It happens. But the manual mode tends to work pretty decent with a single zone system as the OP has, once it's dialed in.

EdTheHeaterMan

Since this is only a garage, you can probably keep it simple. a thermostatic mixing valve with a circulator pumping the mix water thru the low temp tubes mignt be your lowest cost option. You can use one zone valve relay to operate all the BB zones and the circulator for the radiant floor pump with a RIB. Those relays are economical and most technicians are familiar with them.

If this is your existing system. or close enough!

Then this is all you need to make the change

Thermostatic valve and low cost standard circulator pump. Nothing fancy

On the Zone Control just add the RIB to the radiant zone to connect the radiant circulator. No need for a zone valve on that zone since the system pump will not move water thru the mixing valve restriction. I learned that by accident after needing to switch a zone valve head on my system to get heat (temporally) by removing the head from the rad floor zone ands locking it open with the defective head.

This is the simple wiring of a RIB in a Zone Valve control for a circulator pump on the radiant floor zone

RascalOrnery

Ok, thanks everyone, that's along the lines to what I was thinking. I did a self install with radiant and baseboard using primary secondary piping and so I'm familiar with the basic concepts but my zone control is VERY simple and in one instant manual so the diagram Jamie posted is tremendously helpful, hope everyone has a super weekend!

hot_rod

https://forum.heatinghelp.com/discussion/comment/1808695#Comment_1808695

i think the zone 1 pump needs to run also? To keep a supply across the close tees.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1808749#Comment_1808749

AGREE, that is accomplished by the jumper from 3&4 to simulate an end switch when RIB relay operates the circ pump

RascalOrnery

My apologies, I see Ed posted the schematics. Thanks everyone!