DIY Install - Heat only Mod/Con Boiler for Slab Radiant

[George-in-NH]

>[/QUOTE]That would have been very helpful. Does it give much info on how to tune the system after it is in place? I like to tinker....[/QUOTE]

Re Shepner

It doesn't really have a section on trouble shooting but it does explain what each design element is meant to achieve and how it should work. I haven't had to trouble shoot anything yet but feel that there's enough info in there to help me figure things out should I have to.

George

 

[George-in-NH]

So I did finish this in time for warm weather[emoji4]

We did have a mini cold snap so I was able to test it for a bit. It was around 30f for a high temp for a few days. The floor got to 72f. Air temp @ 5 ft was 65f. Very comfortable. I played with the outdoor reset curve selections. At the setting I chose, the hottest the supply temp got was 95ish. The delta was around 20. Flow rates were 4gpm for the boiler loop and 1-2 for floor loop.

I just need to set the throttle for burn tuning and put the antifreeze in. I have access to an old Bacharach O2 meter [emoji106]but it needs a new sensor[emoji107].

So that’s my spring update, I’ll put up some numbers etc when it gets cold again.

George


Sent from my iPhone using Garage Journal

 

[George-in-NH]

I have 9 left over Crete Heat Panels for free see here

Free - Crete Heat 2'x4'x2" EPS Panels for Radiant Slab

I have 9 left over panels from my garage build. Located in Hampton, NH. Message me and I'll arrange a time to leave them out and you can pick them up. Don't want to throw out and don't feel like dealing with selling. George

www.garagejournal.com

 

[yeldogt]

I see a taco control ..... is that doing the ODR? or is the boiler not able to power the pumps?

 

[George-in-NH]

Hi,

The boiler powers the pump for the boiler loop (primary) and the taco powers the heating loop (CH or Secondary). The thermostat, through the Taco, tells the boiler it needs heat and starts the CH pump. The ODR sensor signal goes to the boiler and the boiler controls the temp of the Primary Loop based on the ODR curves.

Some boilers can power both pumps or the boiler loop pump is integral to the boiler assembly.

George

 

[yeldogt]

So your thermostat is an on/off switch?

Typically the boiler uses the ODR thermostat to also control the system on/ off. Secondary pump/s run off the primary -- using switching relay if not direct control.

With a thermostat you interrupt the ODR and typically increase the heat curve as the system is turning off and then needs to rebound.

 

[George-in-NH]

Thermostat is wired into the Taco zone control. The thermostat signal is also output from the Taco to the boiler ZZ input. So the call for heat from the thermostat tells the Taco to turn the zone circulator pump to start pumping and it tells the boiler to make some heat. The boiler controls the fire (modulation) and tells the boiler circulator pump to run. The Outdoor Temperature Sensor is wired to the boiler and the boiler uses this information and the selected Outdoor Temperature Compensation (OTC in Weil McLain speak) curves to determine what temperature the water is heated to in the boiler loop, based on algorithms in its controller. There's a water temp sensor in the boiler.

The documentation provided for the boiler is OK but not great - I had to read it several times before I understood what to do wiring wise.

Seems to have worked well.

I may do a wiring schematic so I don't have to rethink it later on again. This is only my second boiler install and the first one was a direct replacement so it was easy to wire.

George

 

[yeldogt]

My systems are never "off" .... this is where the new pumps excel as they use very little energy. Each house/ building is a bit different .... you can set them up to turn "on/off" based on the outside temp. With outdoor reset -- the correct curve should allow the system to be running all the time for best efficency

 

[George-in-NH]

I think your saying that the best efficiency is when you are able to match the rate heat is added (with an always running system that adds btu's to the floor) to the rate the building looses btu's. An Ideal situation that is a goal but it would be a very impressive thing to achieve with the control system.

I didn't spend a lot of time playing with the curve selection, but the one I choose allowed for long lowish temperature (thru the floor) run times. This boiler only gives the option to choose existing OTC curves, this winter I'll try other ones to see if I can get closer to the "always pumping" goal of just replacing the buildings heat loss.

Are your systems able to accept customized outdoor compensation curves?