wiring a radiant zone off a steam boiler
#1
10-09-08, 05:47 AM
wiring a radiant zone off a steam boiler
I recently had installed a zone of radiant heat off of my existing burnham steam boiler. It is piped to draw hot water off the bottom of the boiler before it becomes steam and circulate through the floor of the kitchen. There are 2 circulators..one to draw the water out of the boiler and into the heat exchanger and another to circulate it into the house. I'm just a little confused on the how to wire it all up. I was told by the plumber to wire it all using an R845 relay. If I have the concept down...the thermostat calls for heat, both circulators turn on. If the water in the boiler is below 180 then the burner turns on, once it comes up to 180 then the boiler turns off....sounds simple of course. I have to be able to make steam and hot water for both thermostats independently or simultaneously....
I have an L4006A aquastat and I was going to purchase an R845 relay...any wiring help would be greatly appreciated... thanks.
I have an L4006A aquastat and I was going to purchase an R845 relay...any wiring help would be greatly appreciated... thanks.
#2
10-09-08, 10:10 AM
Join Date: Mar 2006
Location: Wet side of Washington state.
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Two circulators and a heat exchanger? You are going to have to post some more information. Please describe in detail what you have and include a diagram or several pictures of the piping installation.
To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here. More pictures are always better than fewer. Please have CLEAR pictures and have both close up pictures and ones from a far enough distance that we can see how the various parts are interconnected.
To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here. More pictures are always better than fewer. Please have CLEAR pictures and have both close up pictures and ones from a far enough distance that we can see how the various parts are interconnected.
#3
10-09-08, 10:34 AM
I will try to post pictures tonight, but in the meantime:
I have a Gas Fired Burnham, 240,000 BTU steam boiler.
Radiant is piped from the bottom of the boiler. There is an L4006a aquastat set in the pipe coming from the boiler, but before the heat exchanger. It is set for 180. There is a plate heat exchanger with a Taco circulator mounted to it to draw water from the boiler into the heat exchanger. Water comes up from the heat exchanger and is piped into a mixing valve. The mixing valve is set to bring the water temperature to around 110. Above the mixing valve, there is a second circulator to bring water into the PEX tubing running under the floor. The water makes the loop and comes back down to a tee with one end going back to the cold end of the mixing valve and the other end back down to the heat exchanger. I hope this clarifies things a bit....thank you for all of your help.
I have a Gas Fired Burnham, 240,000 BTU steam boiler.
Radiant is piped from the bottom of the boiler. There is an L4006a aquastat set in the pipe coming from the boiler, but before the heat exchanger. It is set for 180. There is a plate heat exchanger with a Taco circulator mounted to it to draw water from the boiler into the heat exchanger. Water comes up from the heat exchanger and is piped into a mixing valve. The mixing valve is set to bring the water temperature to around 110. Above the mixing valve, there is a second circulator to bring water into the PEX tubing running under the floor. The water makes the loop and comes back down to a tee with one end going back to the cold end of the mixing valve and the other end back down to the heat exchanger. I hope this clarifies things a bit....thank you for all of your help.
#4
10-09-08, 11:13 AM
Join Date: Mar 2006
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I'm going to be leaving the house in a bit but I will work on your solution. Essentially what you want is to have the boiler burner enabled when the radiant system is actually calling for heat. You don't necessarily want the burner to fire unless the water temperature in the secondary (radiant) loop falls to a point where addition heat is required. You also have to co-ordinate the operation of the two pumps. Shouldn't be too hard although it will take me a couple of hours of thought. I'll have more for you tonight.
#5
10-09-08, 03:28 PM
suggestion...how about running the boiler to HX circ. from the boiler cycle call for heat.if the house is calling the radiant can't be far behind to call.this would give you direct stat control of the HX to radiant circulator with the HX already heated up prior to running the radiant.
#6
10-09-08, 03:50 PM
Jim, I'm assuming that on the radiant side of the heat exchanger that you also have an air scoop, water feed, and expansion tank installed ?
The circulator on the boiler side probably should be bronze, is it ?
You should be OK to run cast iron pump on the radiant side as long as the proper O2 barrier PEX tubing was used.
By the way ... 240,000 BTU ? You live in a hotel, right ? I could heat FOUR of my home with that monster.
The circulator on the boiler side probably should be bronze, is it ?
You should be OK to run cast iron pump on the radiant side as long as the proper O2 barrier PEX tubing was used.
By the way ... 240,000 BTU ? You live in a hotel, right ? I could heat FOUR of my home with that monster.
#7
10-09-08, 09:10 PM
On the heat exchanger I have a Taco 007-F5-71FC circulator pump. On the radiant (above the mixing valve leading to the pex tubing) side there is a taco 00R-F6-1FC. On the radiant side there is also a water feed and an expansion tank....not sure what an air scoop is though....Thanks.
By the way....the boiler is pretty huge...it was installed just before I bought the house...it replaced an old boiler the size of a freight train.....the house is 2400 square feet.....I wish it were a hotel though....at least I would have a room to hide in....
By the way....the boiler is pretty huge...it was installed just before I bought the house...it replaced an old boiler the size of a freight train.....the house is 2400 square feet.....I wish it were a hotel though....at least I would have a room to hide in....
#8
10-10-08, 08:59 PM
Join Date: Mar 2006
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I'm sorry I didn't get back earlier but sometimes life away from the computer takes precedence. 
Anyway, the simple scheme is that you may run both circulator pumps in parallel and use the R845A as the interface between the room thermostat and the circulator pumps. The auxiliary contacts of the R845A would be used in conjunction with the L4006A to operate the burner on the boiler. Without knowing the wiring of the boiler burner, the steam pressure control and the room thermostat on the steam system I cannot give you much more advice. If you have a link to (or a picture) of the existing burner and thermostat wiring I can give more specific advice.
Anyway, the simple scheme is that you may run both circulator pumps in parallel and use the R845A as the interface between the room thermostat and the circulator pumps. The auxiliary contacts of the R845A would be used in conjunction with the L4006A to operate the burner on the boiler. Without knowing the wiring of the boiler burner, the steam pressure control and the room thermostat on the steam system I cannot give you much more advice. If you have a link to (or a picture) of the existing burner and thermostat wiring I can give more specific advice.
#9
10-11-08, 07:14 AM
Jim, the pump that you have on the boiler side is cast iron... I believe it really should be a bronze job... by the way, the '1' in both pump numbers is an ' I ' which IFC means internal flow check. Which in this case you really don't need, but it won't hurt anything...
'Air Scoop' or 'Air Separator' is a device that 'scrubs' the air bubbles out of the system and passes them to an automatic air vent. Without them you may not be able to remove trapped air from the system easily.
What kind of tubing did you use for the radiant side ? If you didn't use O2 barrier tubing, you probably should have a bronze pump on that side as well, in addition to an expansion tank designed for radiant systems that do not use O2 barrier tubing (they have a plastic liner to prevent the tank from rusting out from the inside).
'Air Scoop' or 'Air Separator' is a device that 'scrubs' the air bubbles out of the system and passes them to an automatic air vent. Without them you may not be able to remove trapped air from the system easily.
What kind of tubing did you use for the radiant side ? If you didn't use O2 barrier tubing, you probably should have a bronze pump on that side as well, in addition to an expansion tank designed for radiant systems that do not use O2 barrier tubing (they have a plastic liner to prevent the tank from rusting out from the inside).
#10
10-13-08, 08:05 AM
Thanks for the help....just curious, does it make more sense to wire the thermostat through the aquastat and only turn on the circulators after the water has come up to temperature?
#11
10-14-08, 07:46 AM
I have been trying to upload my wiring diagram, but unfortunately am having trouble...I will try to explain it here. 110 feeds a 24V transformer. One leg (blue) is attached to a switch (a light switch mounted to the boiler). The other leg (yellow) is attached to the following: yellow leg of vent damper, yellow leg of gas valve, yellow leg of low water cut off. the other leg of the switch is attached to the low water cutoff and the vent damper. I assume this means that I am feeding these three things with 24V and that I am switching on or off the low water cut-off and the vent damper.
From the thermostat, one leg is attached to the gray lead on the pressuretrol and the other leg is attached to the pink lead on the low water cut off.
The pressuretrol also has a pink lead which is attached to the vent damper.
Lastly, the vent damper has a lead which is attached to a sensor on the boiler right near the gas valve...not sure what this is.
I hope this helps....
From the thermostat, one leg is attached to the gray lead on the pressuretrol and the other leg is attached to the pink lead on the low water cut off.
The pressuretrol also has a pink lead which is attached to the vent damper.
Lastly, the vent damper has a lead which is attached to a sensor on the boiler right near the gas valve...not sure what this is.
I hope this helps....
