Heat Loss From Out Building and Buried Pex

I am heating approx 2200 sq ft, un insulated with huge single pane windows, in frigid temps my coalgun struggles to keep up and on some days it doesnt and my house temps drop down into the mid 60's, I keep the stat at 74...the boiler is about 140 ft or so away from my house in a out building, pex lines buried 4 feet down in sched.40 insulated on the outside. I know I know my house needs some insulating done to it but renovationg this whole house is my project over the next many years and until I get all my outside walls insulated I want something to keep up

It sounds like with your 140 foot underground run you may be losing appreciable heat to the ground.

You need to find out if you are getting extreme heat loss from your underground pex before you sell your boiler. You stated that you insulated it on the outside of the 4" schedule 40. How so? Four feet deep might be an issue also. Find what the temperature differentials are boiler to house and back. Ten degree differential with no load is enough to waste 40 k BTU's more or less. Would make your 115k BTU net boiler a 75k BTU boiler.

There is heat loss at your outbuilding also

dchartt wrote:pex lines buried 4 feet down in sched.40 insulated on the outside

Just to on the same page,you have uninsulated pex in a pipe,do you know if you have any condensation inside the pipe? Have you ever measured the pex temps from the boiler to the house. Do a heat loss/heat load to see what's needed,don't guess,AHS makes 4 different sized multi fuel sizes to meet your heat load.

SCREW WOOD! WOOD SUCKS!

How much coal do you burn per season?

As I recall your house has an old gravity system with huge pipes and radiators.

Scottscoaled wrote:You need to find out if you are getting extreme heat loss from your underground pex before you sell your boiler. You stated that you insulated it on the outside of the 4" schedule 40. How so? Four feet deep might be an issue also. Find what the temperature differentials are boiler to house and back. Ten degree differential with no load is enough to waste 40 k BTU's more or less. Would make your 115k BTU net boiler a 75k BTU boiler.

It has insulation wrapped around the outside, If I were to do it again I would bury the pipe in spray foam, definitely didnt want the lines that are insulated on the inside because if something happens you cant pull a line out to replace....why would 4ft deep be an issue?

never took temps on the pex coming in the house, I know my mixing valve wont let the house receive anything over 165 to 170 and thats an issue also

Rob R. wrote:How much coal do you burn per season?

As I recall your house has an old gravity system with huge pipes and radiators.

this season I have almost 4 1/2 ton burned so far

yes it does, and my boiler isnt wired up to shut the pump off when the water temp goes down so low to let it recover

without gettin rid of all the huge gravity fed pipes would a bigger pump benefit me? there is one rad upstairs that will never no matter what get hot water to it but everything else gets nice and hot

Your water table fluctuates. It could have been low when you installed. The point I'm making is that if your insulation get wet, you will be spending your time buying coal or wood. A lot more than you should have to.

Coalgun won't keep up ,or is the mixing valves low temp preventing enough heat to get to house ? Why have a mixing valve control the water temp going to house ??

the ground here gets wet that deep maybe 4 times a year and it definitely don't happen in heating season, the reason I know that is because I had an outside line buried that deep with a crack in it and it had to rain extremely heavy and hard for awhile to get water in that pipe and it only happened a few times a year

windyhill4.2 wrote:Coalgun won't keep up ,or is the mixing valves low temp preventing enough heat to get to house ? Why have a mixing valve control the water temp going to house ??

so when my boiler is sitting at 200+ I don't melt my pex lines when the pump kicks on

do they make a mixing valve that can be controlled a little better than just turning a black plastic knob in different directions?

Scott's correct on the water table fluctuating unless you're on a hilltop or the like. The first time I buried my pex was about 4' down.

That spring I could tell in February just where the line was, I could have planted a garden almost. The water table had risen.

Brought it up to around 2&1/2' and don't see the line now and use less coal.

I think what is needed now are your incoming and outgoing temps. My AA130 will heat our 1200' house and 1200' of garage with little more than a decent workout.