pumps with zone valves help!

[rancherburn]

I have an owb heating two seperate buildings one has in floor the other is forced air. I recently did some temp drops on the underground lines they're 125' to each building 250' all together. I'm seeing a 5 degree temp drop on both lines when there is no load. with grundfos pump on low i'm guessing about 7 gpm. so that would mean my boiller temp is dropping 5 degrees every 15 minutes. so i was thinking about zone valves only circulating when there is a load the rest of the time circulating just the boiler. i've seen wireless thermostats on line wondering if this would be an easy fix. or don't you guys think i will see enough savings to mess with it. any input would be greatly appreciated.

 

[R W Ohio]

It seems that the underground piping is suspect. 5°F loss is much too much to lose in that length of a run without any load being taken from it.

 

[heaterman]

I have an owb heating two seperate buildings one has in floor the other is forced air. I recently did some temp drops on the underground lines they're 125' to each building 250' all together. I'm seeing a 5 degree temp drop on both lines when there is no load. with grundfos pump on low i'm guessing about 7 gpm. so that would mean my boiller temp is dropping 5 degrees every 15 minutes. so i was thinking about zone valves only circulating when there is a load the rest of the time circulating just the boiler. i've seen wireless thermostats on line wondering if this would be an easy fix. or don't you guys think i will see enough savings to mess with it. any input would be greatly appreciated.

Well here's the math........

7gpm x 8.33 x 5 x 60 = 17,493 btu's lost per hour ........Egad!!

17493 x 24 = 419,832 (per day)

419,832 x 7 = 2,938,824 (per week)

Avg btu content per cord = 21,000,000

21,000,000 x .50 (efficiency....generous for an OWB) = 10,500,000 btu's

10,500,000 / 2,938,824 = 3.58 so.....

Every 3-1/2 weeks you are burning an extra cord of wood provided the info on temp drop and flow are correct.


So what does a cord of wood cost you?

A Honeywell wireless programmable t-stat will set you back around $300 m/l (YTH6320R1009)
A couple 1" zone valves will be around $130 m/l (V8043E5079)
You'll have somewhere in the neighborhood of $5-600 in the stat and ZV's (good pro grade stuff)

So again.........what does a cord of wood cost you?

Hope that helps

 

[rancherburn]

do you think zone valves will give me the resaults i'm hoping for or should i look at replacing the underground lines. When I installed them I ran into ground water perhaps the drainage tile they are in is leaking alowing water to contact the pipe

 

[Clarkbug]

Zone valves will only stop the losses you have when there isnt a call in one of your buildings. During most of the winter when there is a call for heat, you will still have that loss, which is costing you wood.

Since you are in Wisconsin, that is going to happen a lot of the time.

Heaterman did a great job of running the numbers and providing some costs, but if it were my system I would spend that money on fixing the buried lines instead. The groundwater would definitely impact things. If you search here on the forums, you can find people who lay their lines, then have a sprayfoam contractor come in and foam the trench instead of running in a drain tile. This keeps the return line from tempering the supply line, but also is a great insulator relative to other methods (especially the foil bubble wrap option). It might be a little late in the season to go digging up your lines, but my guess is thats where your issue is right now.

 

[heaterman]

do you think zone valves will give me the resaults i'm hoping for or should i look at replacing the underground lines. When I installed them I ran into ground water perhaps the drainage tile they are in is leaking alowing water to contact the pipe

Absolutely.

If you have ground water I would highly recommend something like Microflex tubing that is and will remain 100% waterproof. About $18/ft for 32mm tube (bigger than standard 1" pex) but worth every penny. .......Let me put it this way. Of the thousands of feet of underground we have dug up and replaced for people, none of it was Microflex. (Watts R-flex is the same thing)