Need help with boiler setup

Hoping for some help here, I have PB105 pellet boiler and an ancient old oil boiler backup. Currently they are plumbed in series with only one aquastat which is located on the oiler. Only reason it is in series is because my installer couldn't figure out how to make the oiler stop running constantly.

I believe I need to have them plumbed in parallel along with a minimum of 2 aquastats.

I found these diagrams here http://www.hillsideenergy.com/Downloadable files/Woodboilerpipingdiagrams.pdf but I don't have any storage, or any DHW. Mine should be very simple just one zone. It looks like in those diagrams they have the thermostat hooked to a switchable controller (to select main boiler, backup only, or main with auto backup) and each boiler has its own aquastat as well. I'm just getting very frustrated with my situation because on top of all the usual PB105 problems, I am still using a bunch of oil, and I can only set my oiler to run at 135 max because of the single aquastat. I'm having a meeting with my installer and my dealer friday and I would like to have my cards in a row to get this handled. I should've just done it myself to begin with and I'm pretty sure I'm gonna end up doing it anyway. Thanks in advance guys.

Wayne

No DHW, I have a seperate tankless setup. I will check it out right now, thanks!

BioHeat Sales Guy said:

Your first choice should be the plumbing design recommended or supplied by the manufacturer.

If for some reason that doesn't work, have a look at "Solo 2" at http://www.woodboilers.com/admin/uploads/public/Solo Plus Plumbing.pdf

Just use an aquastat located at the pellet boiler to lock out the TT terminal on your oil burner. That way you can leave the oiler's aquastat at 180 and the oiler only comes on when the pellet boiler temp drops below it's aquastat set-point (140F for example). Since you have a tankless water heater, there is no reason to keep your oil boiler hot - just produces more uncontrolled heat loss. Solo 2 accomplishes auto back-up, two boilers, cold start oil boiler.

Chris

Click to expand...

That is exactly how I'm trying to get this to function. Thank you for the link. Unfortunately the installation diagram for the PB105 doesn't show any of the controls needed to get the boiler to operate in the specified manner. I'm sure that is why I'm having such a problem up here.