Outdoor Wood Boiler Plan & Install

What is the aquastat controlling? Is it determining when to fire your existing heat?

 

It looks like I'm a little late to the party here but I was going to suggest the door to your owb open to face the prevailing winds that way when you open the door to load, you don't have a bunch of smoke blowing directly into your face.

 

Aquastats are used for lots of things. You'd likely have one to keep the OWB in operating temperature - I'd think that would come with the OWB. They are also used to switch control from one boiler to another depending on water temp changes.

 

The OWB should have its own aquastat. The one inside must be controlling something inside....just not sure what. Typically the loop from the boiler just flows through the air/water HE without consideration of water temperature. Maybe there's an automatic bypass of the HE in play here?

 

I think the Aquastat on the inside, is in case the outside boiler is not making enough heat to keep the house at temperature.

 

Probably so. Probably bypasses the A/W HE so he isn't using the indoor furnace to heat the OWB if the house calls for heat and the boiler temp is below "X".

 

Yes, that’s exactly right, from my understanding. Since the hot water from the boiler is going into a heat exchanger in the duct work supply line, the aqua stat is going to measure the temp of the duct work air and tell the electric heat not to kick on but rather just the fan. In the event the OWB doesn’t have heat (fire go out, burns down to coals or I’m out of town), the aqua stat would control the heating element to kick on in the furnace. That’s why I have to have the HVAC guy hook it up, it’s all got to be wired and that’s definitely not my specialty! If it was water looping through to radiators there would be no need for the interior aqua stat. And someone asked earlier- yes, the unit comes with an aqua stat of it’s own.

 

Well, that's not what an aquastat does. Thermostat yes. Aquastat turns things on and off based on the temperature of water, not air. He may be using the aquastat to measure the boiler supply temp using that to fire the furnace.

Just keep in mind that whenever the electric/gas/oil kicks on you will be heating your boiler water with it too....unless you have a thermostatically controlled bypass.

 

Not sure what OWB you are using, but my Hardy just uses snap disk to trigger my propane furnace in the event the Hardy goes out. It works off a temp differential and sends a signal back to propane furnace. Just for information purposes Snap Disc or Snap Action Thermostats - Comstat, Inc.

Hold on I'll get a picture of mine.

 

Snap disk.
Relay.

 

Getting the fittings and circulation pumps all ready and mounted, for the house and the garage apartment.

 

The next step will be lifting the boiler off of the trailer and setting it in place on the pad, and getting the connections done.

 

Looks like a beast.

 

Once I get it all in place and hooked up....let it snow, let it snow, let it snow! ⛄️. But until I do, a couple more weeks of mild weather is appreciated, Mother Nature!

 

Got the boom truck to lift it into place, and fed the PEX line up through the back. Cut the black drain pipe flush with the stove.

 

The photo of you dropping it off is awesome you have a beautiful barn and farm

 

Can you explain this one a little more for me? The thermostatically controlled bypass... how it functions, where would it be installed in the loop and are there pluses or minuses to having it?

 

The most simple and typical install for an OWB has a pump mounted on the back of the boiler that pumps the loop continuously. This loop goes from the boiler, to the water heater, to the furnace heat exchanger, then back to the boiler.

This is fine most of the time, but if the boiler water temperature isn't hot enough and the backup heat source is called upon, it will be blowing air across your heat exchanger, and the water in your heat exchanger will still be going back to the boiler. Heat exchangers work both ways...they can absorb heat just as well as they dump heat.

Ideally, if you plan on the backup heater kicking on occasionally, you would have a bypass valve that would take the furnace heat exchanger out of the loop if the water temperature coming in from the boiler drops below a certain point. Make sure you use the incoming temp, as the outgoing temp is going to be up and down based on if your furnace blower is running.

The plus is you avoid heating boiler water with your backup heat source (although if you had a major boiler failure during a really cold snap this might be a good thing).

The minus is extra cost and another potential point of failure.

 

Hooked up for the domestic hot water, just 2 of the 3 water to air heat exchangers to install and hook up and ready to fire it up! Hopefully this weekend- fingers crossed!

 

Looks good!!