4acrefarm said:
thanks for the info. My output temps are low because i have a snap disc that turns on the circ at 150*. I will change this to 180* immediatly. What is the lowest stack temp I should run? Is an ir therometer an accurate way to measure? What kind of mixing valve and how much$?
Yes, upping the circ turn on temp should help. One caution you MAY need to look at, depending on how your system is set up, is to watch the temps on your radiant floors - make sure you don't exceed the maximums for comfort and preventing damage... Optimum stack temps seem to vary, but 3-400*F seems to be a good range, w/ up to 600*F being OK... Best way to measure it is with a probe type thermometer that gets it's reading from the middle of the pipe. Shooting the pipe with an IR unit will work, but the results will probably be 1-200*F low...
However the big thing that you should be worrying about, is your boiler water return temp - If that is low, you will rapidly destroy the boiler, regardless of how other the other temps are. If you get the return temp into the right range, it is quite possible that the other temps will largely correct themselves...
As I said earlier, there are MANY options for how to do boiler return protection, with a wide range of price tags and features. Which one is best can be the subject of a great deal of argument, and will also depend on both how your system is plumbed currently, and how you want to change the plumbing to do the return protection. All work on the basic idea of mixing hot boiler supply water into the return water in order to bring up the return temperature to at least 140-160*F, but how they do it varies.
If you post a diagram of your current system layout, we can possibly suggest some options. Computer drawings are nice, but not essential - making a pencil and paper drawing, and taking a photo of it will do if that is what you feel most comfortable with.
We will be especially interested in the "near boiler" piping - what size and material, where are the pumps, zone valves, and other such fittings. We aren't as worried about the details of your loads and floor loops.
Gooserider