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[AnotherNewbie]

Hi All, I've been reading this forum for great advice and help in setting up my furnace and trying to reach maximum efficiency, but I've reached my wits' end and have no idea what else to try. 

Here's my problem.  I have water heated to 175 degrees in my furnace, and at the supply line immediately outside my furnace the water is measuring only about 155 or 158 degrees...  This is water that I'm checking as soon as it comes out of the furnace and even before it goes through the pump.  I have a small drain installed on the plumbing above the pump and I pull some water from it and get readings that are sometimes 20 degrees less than the water inside my furnace. 

The way I'm testing the water is with a long probe thermometer that I drop down into the water jacket through the fill spout on top of the furnace.  I then pull water out of the 'drain' above my pump into a cup where I use the same thermometer to measure and get a change of 15-20 degrees. 

The furnace is about 220 feet from my house, and, being a newbie who decided to do the entire install himself, I don't have any way of getting water out of the system inside the house to check the temperature, but I do have a copper sidearm heat exchanger on my hot water tank that I can get a reading on with an instant read thermometer and I seem to be getting about a 2 or 3 degree drop between the water that's actually coming out of the furnace and the water in the house. 

I have a Grundfos UPS26-99FC, 3-Speed Circulator Pump (which is brand new - I just replaced a Taco 009 pump to try and get the numbers up) pushing water through 1" pex.  The Furnace itself is a "Freedom Eliminator 4800" dual fuel furnace.

If anyone has any ideas what could be causing me to be getting such a change from the water to the supply line, I'd very much appreciate any thoughts!

I bought my furnace used, and installed it myself by copying the set up of the prior owner.  After reading page after page of information on this site, I've discovered that his set up wasn't quite right for my needs (I have the furnace about 3 times as far away from the house as he had it) and so, thanks to the wealth of information on this site, I've increased my efficiency some, but this last piece seems to be the most important.  If I could get 180 degree water into the pump, I could get it into the house, but unfortunately, so far I can't do it.  Any help is appreciated!

Thanks in advance.

[slimjim]

More than likely your return water from the house is not mixing well with the water near the Aqua-Stat probe, in other words the probe itself is in a dead spot, maybe try reversing your lines and see if that helps

[hondaracer2oo4]

Slim, Sounds like he has just the opposite problem if I am understanding it correct. Temp in the furnace is 175 but he can only get the temp leaving the furnace to be at 158? I do agree though that the water sounds as though it may not be mixing well. I am going to guess that the aquastat probe is not located near the supply line leaving the furnace? The furnace may have a design problem similar to Shavers where they installed all of the supply and return lines on the back where they placed a full height rear plate on the back of the firebox which allows water in the front to boil but has a hard time bringing that water to the back of the stove where the supply line feeds from. I think you should also try reversing your supply and return lines to try and get better mixing.

[ITO]

 I am assuming that your aquastat probe is a wet well probe in a wet well? I would double check that your aquastat is sensing (working) properly. If it's easy take the probe and put it into a cup of hot water with your thermometer and see if they agree to start with.

[AnotherNewbie]

Thanks for the quick replies!
Slim, I moved the return line further away from the supply line this weekend and am still having the problem.  My return line now enters at the bottom of the furnace and the supply line is close to the top whereas before the two lines were close together and my thought was that the cold return water was mixing with the hot water right at the supply, but moving the return line doesn't seem to have helped. Maybe reversing the lines would still help though?
Honda, I'm interested in this design flaw of the Shaver furnaces and wondering if that could be part of my problem.  Unfortunately, Freedom doesnt make furnaces anymore and so I don't know much about (nor can I find out much about) the internal design of the stove. If there is a plate on the back of the furnace it might be causing the water at the back of the furnace to stay cooler than the front, but my aquastat is in the back also, so I would think that it would effect that also.

ITO, I thought that perhaps the aquastat was faulty, so I checked the water in the tank against the settings on the aquastat and it seems to be reading accurately. 

Is there a "simple fix" that anyone knows of if I do suffer the same design flaw as the shaver system?

Thanks again for the quick replies and if more information from me would be helpful, please let me know. You guys are awesome.

[ITO]

 Usually the supply pulls off the bottom, return on top. My comment about the aquastat also had to do with the correct probe and that the well was matched to what style probe the stat has.

[slimjim]

I think that this is one of those things that the manufacturers should be paying attention to, good mixing of the return water on any boiler is key, we installed many indoor Italian boilers a few years back to the manufacturers specs and were getting 40 degree difference between the front and back of the boiler, to correct the issue we simply re plumbed the supply line off the front and the problem disappeared, after speaking with the importer they changed the install manual!

[AnotherNewbie]

Just thought I'd throw a quick update on here and thank you all again. I've been tinkering with the furnace again and think I'm getting close to efficient.  After reading all your comments and checking off the things I could check off, I spent some time researching the problems with the Shaver furnace design mentioned earlier by Honda. I think that my furnace might suffer the same problem as some of the shaver furnaces so I plumbed my return line (temporarily) directly into the fill spout on the top of the furnace and far away from the aquastat and supply line.  Almost immediately I was able to get the water above the pump to within 5 degrees of the aquastat.  Now I just have to figure out the best way to permanently return the water to the front of the furnace.

Thanks again everyone.  I have a feeling this is going to save me a lot of headaches and backaches when I start burning much less wood!  Thanks again.

[victor6deep]

Set aquastat at 200 that will get your 180 temp.

[hondaracer2oo4]

Certainly sounds like it was as simple as a water mixing issue. Why not just use the fill as the permanent return? Do you actually use the fill to fill the stove? I have my fill line T'd into the return line back to the boiler with a ball valve. I feed the ball valve off of the domestic water. When the stove needs to be filled back up I simply open the ball valve for a minute or so.

[RSI]

If you move the return, just make sure it is below the top surface of the water in the boiler. If it is dropping in, it will mix air into the water.