Central Boiler Trenching - What To Bury?

LegendsCreekFarm · February 03, 2016, 02:15:22 PM

Hi everyone. I am hoping for some quick advice as this is very last minute and I am rushing to get everything I need before next week.

I bought a 6048 boiler which isn't installed yet (waiting until Spring), however, the guys I hired to install a septic on one of my buildings called to say they are installing it now and offered to dig my boiler trenches for me as the excavator will already be here.

SO, here is what I am doing. Placing the boiler in a central location to 3 of my buildings. I am running thermopex lines to each of the 3 buildings and leaving them sticking out of the ground at the boiler area, and building areas (next to the foundations I will be later running them through) until I am ready to start hooking them up.

I know that the boiler needs electric, so should I run a direct burial electric line to the boiler also when I bury the thermopex? I only need 1 electrical line correct? If so, I will just run the electric to the building with the easiest access to it's panel.

Now, for the thermostats, since I have 3 buildings, will I need to run a direct burial thermostat wire in each trench so each building has it's own thermostat hooked up to it's corresponding pump?

I am running the thermopex through PVC and burying it 3 - 4 feet deep so I can drive over it with my machinery. If I need to run the electric and thermostat wires then I do not want to have to dig it up later, so am hoping that with all your advice I will be able to run it with the thermopex next week.

Thanks a lot.

gspren · February 03, 2016, 02:48:25 PM

I kept all of my pumps in their respective buildings with valves on either side for easier access and no need to bury thermostat wires. On mine the only electric needed at the stove is for the stove itself, blower and controls. While the trenches were open I used them to get water to an out building.

LegendsCreekFarm · February 03, 2016, 02:52:28 PM

So if I choose to house the pumps in the buildings, rather than on the boiler, I can keep the thermostats wires out of the trench?

It seems that 1 electric line should be sufficient, correct?

beenthere · February 03, 2016, 03:23:42 PM

Run a 1/4" nylon rope through the PVC pipe so you can pull more wires in the event you want more.

doctorb · February 03, 2016, 05:37:46 PM

I agree with keeping the pumps in the buildings. I would ask, what backup heat do you have for these three buildings. If you already have a heating system in place, then the thermostats within the building are already wired and in place. All you have to do is create a system to transfer the energy from the OWB to your existing heating system. The water from the OWB circulates continuously and is not tyurned on and off by a thermostat.

Simplistically, the OWB's job is to fool your existing heat source into NOT kicking on. It should never receive the signal to burn oil (or gas or whatever) because the OWB heat keeps the temp of the furnace warm enough to prevent it.

But beenthere is a smart guy, and laying an extra conduit is never a bad idea.

Simplicity · February 03, 2016, 08:28:35 PM

I just ran one wire to my 6048. I have the (3) pumps at the boiler. The guy that installed mine told me people like it better at boiler so you don t hear the noice of the pumps in house or where ever.

Ljohnsaw · February 03, 2016, 08:39:19 PM

So IF you put your 3 pumps in the OWB building, could you get away with one pump and a manifold? Just asking as you would use less electricity running one (preferably variable speed) pump than running three individual pumps. Or does it get too complicated that way?

I used to have three pumps on my pool for various things and replaced them with one vari-speed and a couple of electrically controlled valves. My electric bill dropped a couple hundred a month - enough to pay for the upgrade in about 8 months.

Simplicity · February 03, 2016, 08:50:38 PM

I am not sure about putting one pump and a manifold. I do know that my electric bill, goes up maybe $20 a month when I fire up the boiler in fall.

gspren · February 03, 2016, 09:49:24 PM

The circ pumps use very little electric.

Old Dog · February 03, 2016, 10:57:22 PM

Since you don't have the job spec'd out yet, I suggest you install a separate conduit for power and control wiring and oversize it to handle whatever you dream up later. 1 1/2 or even 2in sch 40 pvc conduit is cheap insurance relative to what you are going to pay your excavating contractor. You'll be able to pull extra wires and leave a pull cord in for any future needs too.

Ljohnsaw · February 03, 2016, 11:38:35 PM

Quote from: Old Dog on February 03, 2016, 10:57:22 PM
Since you don't have the job spec'd out yet, I suggest you install a separate conduits for power and control wiring and oversize it to handle whatever you dream up later. 1 1/2 or even 2in sch 40 pvc conduit is cheap insurance relative to what you are going to pay your excavating contractor. You'll be able to pull extra wires and leave a pull cord in for any future needs too.

Be sure not to mix high and low voltages in the same conduit. Put a 1" or so for your low voltage. Also, around here, if you are going to run both electrical (120/240) and water in the same trench, they are supposed to be separated vertically by a certain amount, which I don't remember off hand. And just for future fun, I'd lay a strip of that yellow caution tape ribbon about a foot down from the surface. Then, when you're digging a few years from now, you know where things are at!

LegendsCreekFarm · February 05, 2016, 11:35:07 AM

Thank you very much for the input.

I am going to install 3 separate lines of thermopex to the 3 buildings, and will run a separate PVC to house the electric line to power the boiler. I will not be running thermostats as I don't have a problem with them being in my buildings (I have boiler rooms in each building for oil hydronic heat).

I have a few more questions about how I am trying to plumb this to make it easier but I will post next week.

Thanks again

NWP · February 05, 2016, 04:13:00 PM

I buried a 1" PVC line with my PEX that runs from the house to the Heatmor. I tied a string around a balled up paper towel and stuck it in the end of the PVC that was at the stove then stuck the shop vac hose on the other end in the house. It sucked the string into the house in about half a second and I pulled the electric wire back.

Ljohnsaw · February 05, 2016, 04:43:49 PM

Quote from: NWP on February 05, 2016, 04:13:00 PM
I buried a 1" PVC line with my PEX that runs from the house to the Heatmor. I tied a string around a balled up paper towel and stuck it in the end of the PVC that was at the stove then stuck the shop vac hose on the other end in the house. It sucked the string into the house in about half a second and I pulled the electric wire back.

I used a plastic grocery store bag to go 350' - worked but not great. Since then, I ran across a special thing just for that. It is a 3 or 4 inch "arrow" that has a lot of fine string wound on it. You tie off the lose end and either blast it with compressed air or pull it with a vacuum. The string unwinds as it goes so it is not pulling anything and gets lighter as it goes. Then you use that string to pull successively heavier lines until you can pull your electric wire.

stumper · February 06, 2016, 05:50:29 PM

I would bury the conduit. I buried an oversize conduit and an extra when I did my install. 100 feet of 1 1/2 conduit is only $40 to $45. I seem to recall I paid more for a foot of the thermopex then I did for 2 runs of conduit. Cheap money. I also ran an extra wire so I could have 220 at the boiler if I needed it. I have since added a generator receptacle at the boiler. Now if I lose the power that is where I power the house from.

In your case I would install 2 to the primary building and 1 to each additional building.