CIrculator Pump Controlled with same thermostat as furnace blower.

[Geigs]

Hello, I am brand new to this so forgive the stupid questions. I am looking for some thoughts on how to have my in-house air thermostat (24v) run both my furnace blower and my grundfos circulator pump. My thinking behind this is I am wasting a bit of heat having the pump run all the time instead of kicking on when my blower kicks on.

Here is a little about my setup:

-Central Boiler Maxim M250 Pellet boiler, 90 gallon capacity, no other water storage. Installed in attached garage
-1" Pex running from boiler, about 60 ft into basement on opposite side of the house
-185k btu heat exchanger in the plenum of my oil furnace controlled by a simple 24v thermostat that kicks on the blower when my house calls for heat
- Pex runs back to the boiler.
-single smaller grundfos 3 speed pump

I realize that the hot water always circulating isnt a bad thing as the radiant heat off the lines is still in my house, however with the m250 boiler, it is picky as to the temperature of the water, it kicks on after a 2 degree drop so I notice is is flopping back and forth between medium and idle. I have adjusted the controller the best I can to try and keep the unit running at medium as the manual recommends.

My thoughts are if it doesnt circulate, it will hold the temp, it will only kick on when the house calls for heat, let me know what you think. thanks!

 

[Eric Johnson]

I have a circulator that pumps water from the supply down into the return of my boiler. When the return temp hits 160 degrees, it turns on the main circulator that gets the hot water from the boiler in the garage into the house. So, the circulator is only on when the water temp at the bottom of the boiler is at 160 degrees. This allows it to maintain temp before sending any heat into the house. But once the temp exceeds the 160 set point, the pump runs continuously.

This serves two purposes: It allows the boiler to maintain temp, and it only pumps hot water into the house system.

How this relates to your question I'm not sure. What you're proposing might work, there's probably a more efficient solution. How about allowing the blower to kick on only when the water temp hits a certain set point? With constant circulation, you can monitor the temp and control the fan with a strap-on stat, to make it simple. If you set up like mine (recommended for longer boiler life), then activate the fan circuit when the main circulator comes on, since you know the water will be hot. Either way works, except that with my somewhat more complex approach, you're never pumping cool water into the house. Of course, your room stat would have to control the blower once the aquastat hits the set point.

 

[Geigs]

Thanks for the info. I do have the thermostatic valve that central boiler provides to ensure the temp of the boiler water never goes below 150. It will bypass my heat loop in the event the temp drops that low. In my case that would only happen if the power is out. My boiler temp never drops below 175 when operating. It is always pumping hot water continuously through my Hx in my plenum. This is working fine, my main thought was if I eliminate the constant circulation and only circulate when my blower is running, my boiler would maintain its high limit of 185 longer, instead of it going through multiple burn cycles just to keep up to the radiant heat loss through the lines.

 

[Tennman]

When I added storage this season I added two RIB devices to control the demand circ pump out in the barn. I used a RIBU1C at the blower to make a closed contact when the tstat calls for heat. I ran CAT5 from that device to the boiler barn ~180' away. I have a RIB01BDC relay that provides 120VAC to a standard wall plug. Our circ pump has a standard male plug that plugs into the relay powered wall plug. Cost about $80 for the RIB devices and I bought plastic electrical boxes to house everything. Google Functional Devices Inc. to read about these devices. If I was smarter the RIBU1C may be unnecessary. Works great and cheap. Merry Christmas.

 

[Geigs]

That sounds like what I'm interested in. Thanks for the info i will check it out!

 

[surefire]

When I added storage this season I added two RIB devices to control the demand circ pump out in the barn. I used a RIBU1C at the blower to make a closed contact when the tstat calls for heat. I ran CAT5 from that device to the boiler barn ~180' away. I have a RIB01BDC relay that provides 120VAC to a standard wall plug. Our circ pump has a standard male plug that plugs into the relay powered wall plug. Cost about $80 for the RIB devices and I bought plastic electrical boxes to house everything. Google Functional Devices Inc. to read about these devices. If I was smarter the RIBU1C may be unnecessary. Works great and cheap. Merry Christmas.

Tennman, would you please post a wiring diagram of this setup? Could the remote circ pump be triggered from multiple tstats or aquastats? Thanks.

 

[Tennman]

Activating the pump relay by multiple tstats may be an advantage for having the RIBU1C I hadn't thot of. I think if I was more controls smart maybe the 24VAC from the tstat could have triggered the relay 180' away. Dunno. I am definitely NOT a controls/electrical guy but this is working flawlessly. I think I have a hand drawn schematic in my notes that I can scan Monday and post or email. BTW, I'm humbled and amused anyone would want controls ideas from me. Best wishes (don't believe in luck).

 

[surefire]

Oh okay! I think I see - you used the dry contacts to trigger at 180'. So if I had multiple aquastats etc, I could run them all in parallel for N/O, or for fail-safe (accidental broken wire) I could run them all in series and use N/C. (I think...)

Do you have any concerns about the water sitting stagnant in your underground lines for too long and freezing? I guess a cycling timer could be used to trigger every so often.

Tennman, please do send along your drawing, so I can see if my guesses are correct.

Sorry to the OP if this is too unrelated.

 

[NCFord]

I did exactly what you are trying to do. All I did was run some thermostat wire from the air handler(hooked to the fan control t-stat wiring from house t-stat) to a relay at the back of my boiler which then turns on my storage to house pump. No fancy controls or anything. I think you could also go right from the house T-stat if you had access, I did not. Anytime the house calls for heat and the fan kicks on the pump from storage to house kicks on.

I think on my T-stat the green wire is the fan relay, though it can vary....a lot.

 

[Armaton]

Taco 1 zone switching relay should do the trick, I would think. About 50 bucks.