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[trz]

I have a post in 'general' about my w/w plate exchanger and water temps, and got to checking some water temps and this is what i've found my. My furnace water as soon as it enters the house is 150 and the thermometer on the stove was reading 170 at that time.   So, I'm basically loosing 20 degrees between the stove and house.  that's about a hundred feet and i have it about 40-48 inches under ground.  I'ts Hawkens' 'pex/al/pex wrapped in i think 3 layers of whatever that is they use and housed in the black plastic flex pipe.  The stuff they sell.    My question is how can i make that more efficient , I'm sure it would be a major job digging it back up, but, is there something i could do to insulate it better if i were to dig it up?

[AirForcePOL]

That's a lot of heat loss in just 100 ft.  I know what you should do, and what I should have done and that is to buy the ThermoPex or something similar.  However, I have a feeling that you are just like me and all about saving a penny where you can.  That stuff is pretty expensive.

I recently insulated my line with that foam wrap around stuff that you can buy at Menards.  I haven't checked what kind of heat loss I am getting but I hope it's not that much! You could get that reflective bubble wrap insulation and try wrapping your pipe in that.  I recently saw a thread where someone had made their own.  You might want to try that route. 

[Johnv656]

Are you going by the thermostat reading on the front of the unit and comparing it to the line coming into the house?
How are you obtaining the temperature from the line in the house?  Temp. gun?

[Scott7m]

It sounds like you have perhaps got water into your pex package, but keep in mind u need to compare on a pex line at the back of the stove, and on a pex line when it gets inside to be accurate, if your not doing that and going by the aquastat then shooting it with a heat gun inside, that can be way off

A high quality 3 wrap should loose less than 2 degrees in that run

A high quality 5 wrap looses about .5 degrees per100ft at a flow rate of 5gpm

The foam filled line such as thermopex or logstor loses around .7-.8 in a similar test.

Trench depth don't mean squat, this test was done on top of the ground, once the heat escapes its gone, whether it be to the atmosphere or soil, one of the biggest mistakes folks make is going to deep and getting down into the mucky water table, when you get down in the mud it wicks heat away much faster, kinda like going outside in the cold and havin someone throw a bucket of water on ya

[trz]

So, what i actually did was take the thermometr reading on the front of the stove for the furnace temp and i drained some water out of the system where it enters the house and took that temp. with and candy thermometer.   Now, you're going to tell me thats not the most accurate way to get my temp. readings?  lol. 

 I guess i'll get a ir gun.   But, i tried an inexpensive  ir gun from home depot one time and couldn't get any consistant readings  so i returned it.    Do i need an expensive one?

[willieG]

i think your candy thermometer is likley close

[RSI]

Where is the pump located and what model is it?

If you are actually getting andywhre close to that much drop, my guess would be either the pump is going bad or partially air locked or one of the heat exchangers is getting plugged.

[MrDan27611]

I'm no expert but IR guns can give false readings. Whatever you use, you should use the same tool at both ends so that any variance isn't between measuring devices. Just one more thing to eliminate.

20 degrees makes me think it's a measurement error, not an actual loss. I had old pipe in the ground with effectively no insulation like bare copper in dirt, distance of about 100 feet. I was loosing about 5 degrees so 20 is pretty dramatic.

[willieG]

I'm no expert but IR guns can give false readings. Whatever you use, you should use the same tool at both ends so that any variance isn't between measuring devices. Just one more thing to eliminate.

20 degrees makes me think it's a measurement error, not an actual loss. I had old pipe in the ground with effectively no insulation like bare copper in dirt, distance of about 100 feet. I was loosing about 5 degrees so 20 is pretty dramatic.

a 5 degree drop or a 20 degree drop could actually be the exact same amount of btu loss.... to determine the actual btu loss you need to know the temp drop and the gpm being pumped. if you were pumping 5 gpm and losing 5 degrees that might be the same as losing 20 degrees and only pumping 3gpm (not actual figures)

[trz]

so, lets say i really am losing close to 20 degrees in a hundred ft. at 5gpm  what can  i do to remedy that situation? 

[willieG]

so, lets say i really am losing close to 20 degrees in a hundred ft. at 5gpm  what can  i do to remedy that situation?

dig em up and replace them or if you can live with losing all that heat" speed up your gpm to deliver more heat to the house

if you upsize the pump to deliver say 8 gpm teh heat loss will be the same (or slightly more) but because you have increased teh gpm you have also increased the delivery of btu's

lets say at 5 gpm and 180 degree water you are sending 50,000 btu per hour to the home and you are losing (not actual just a figure) 25,000. so that leaves 25,000 to the home as well. if you increase the delivery to 8gpm that would be close to 80,000 btu per hour to the home and maybe only increase the loss marginally. lets say it increased the loss to 30,000 that would now still leave 50,000 for the home.

this method would work, but your wood consuption would be huge.

1 degree heat loss would be the same as 1 degree in rise for figuring...1 btu raises 1 pound of water 1 degree F Works in the opposite direction the same. 1 gal ==(for easy figures) 8 pounds, 5 gpm = 40 pounds a min going through the lines so for every degree of loss = 40 btu x 20 degree loss = 800 btu per min...48,000 btu per hour...1,152,000 per day...x 150 heating days=172,800,000 btu per season...that is more than the average home uses. so you would be using over twice the wood as a normal year with good underground lines (if my math is correct?)

[boilerman]

It's may be worse than that. If you are losing 20 degrees coming in, you are also losing 20 more degrees on the way back to the boiler!
Major heat loss and extra wood consumption.

[boilerman]

I lose less than 1 degree total coming in and back out to the boiler when nothing drawing with my urethane filled thermopex after 10 years of use.
85 ft in and 85 ft back out total run. It cost me more at the time, but its been worth every penny and log of wood it has saved me.
If/when you replace do it right. Worth it in the long run.

[Johnv656]

I thought the same with my Hawken OWB that I was loosing 20 degrees by the time it entered the house.
Thermometer on OWB reads 170, and I used a temp gun on the line in the house and get 150.
Last night I used the temp gun at the OWB line of the pump and at the house line. Both read 150. So there is no 20 degree drop using a temp gun.

So tomorrow I am going to pull actual water out of the OWB and at the filter in the house and check with a manual thermometer.

I am thinking either the aquastat is not reading properly?
The temp gauge in the front of the unit is bad (off 20 degrees)?
Or possibly I have a pump that is weak?

No Jacking your thread here, but sounds like we have identical problems. Actually have the rep coming out tomorrow also.

I am very happy with the overall performance.

[Scott7m]

There is nothing wrong with it then if both are giving you the same reading.  The water inside the line is likely exactly what it says it is.    You can't read water temp through lines.  You can try it n pex it will give you one temp, on copper another temp, on black pipe another temp. 

I have a strap on temp sensor that's insulated like crazy and it's always 10 degrees below actual temp, and ir guns are far less accurate