New to forum and wood boiler

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NHarborist

New Member
Dec 15, 2022
8
NH
Hey all, great site! I am new to outdoor wood boilers, not with heating with wood though. We just installed a Crown Royal 7300e. Install was pretty smooth, I like the ease of use of the boiler. However, I am still hearing my indoor boiler kick on ( this is so frustrating) We live in an old house with a new addition. The addition is base board heat and runs on its own thermostat. Old part has radiators. When I call for heat with the old side thermostat, the boiler kicks on immediately even though oil boiler water temp is satisfied. I turn stat down, boiler shuts down. Any insight would be helpful, thank you and looking forward to this site.
 
Definitely need a diagram, some of the hookup diagrams out there are not that well thought out, many of the concepts run wood boiler water through the oil boiler to keep it hot but it can cause issues. Frequently the oil burner needs to be equipped with a normally closed relay that is pulled open when the wood boiler is running.
 
Here are a few pictures of plumbing and wiring of boiler. It seems very simple in design, I feel like I'm missing something though. I have hi and low limits set @ 150-130 on oil boiler. There's one circ. Pump that feeds a loop to base board. Radiators are all fed off supply line. Their thermostat is wired into box right next to burner. Apologize if I'm not using the right vernacular, or missing pieces. Thanks again.

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What we really need is how its piped. Show how the water goes into the oil boiler and where it comes out then do the same with wood boiler and then show all the pipes. I made this up recently for a friend in similar situation. It may not be exactly the same but may be close and then you can mark it up if you have access to a scanner. In this case, I recomended a new normally closed relay to be installed on the black wire between the burner and the boiler controller. The oil boiler is still controlling the thermostat but the relay keeps it from running the burner. The only tricky part is figuring out on the oil boiler where to get an electrical signal to pull open the relay. It may be a 24 volt AC signal or a 120 VAC signal. Therefore the relay may need to be a 24VAC to 120 VAC or 120 VAC to 120 VAC NC.

There may be an aquastat on the wood boiler that turns on a pump when the wood boiler heats up, that could be used or you may need to install one. Ideally you put the aquastat in what is called a thermowell on the wood boiler but in pinch you can install one strapped to the inlet pipe and covered with some insulation. Its very dependent on you wood boiler. If the wood boiler is not being used, the relay is not powered and the oil boiler works like normal except when the wood boiler is warming up. where it could cycle on and off once or twice on occasion. The down side with the set up in the diagram is that hot water from the wood boiler is going through the oil boiler and give up heat that is going up the oil boiler stack.
 

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Looks like I'm missing a lot of pieces according to your schematic. I have an aquastat on wood boiler. Supply with circ pump out of wood boiler into heat exchanger and return out back to wood boiler. The heat exchanger is inline with return line of oil boiler with a ball valve forcing boiler water through heat exchanger. The only electric I ran was a 12/2 line to power wood boiler from main panel in house. I'm gearing up for snow, I'll get pictures when I get a minute. Thank you for the reply
 
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It sounds like your oil burner is wired to fire whenever the zone is running... That was a common way to do it with hot water baseboards because you could turn down the low limit and save some energy but still get hot water when there was a call for heat. Unfortunately that won't work right if you have 2 heat sources.

As peakbagger implied at a minimum the oil boiler should be set up to be disabled whenever the wood boiler is operating. If you use an aquastat for that you also need to be careful so you're not inadvertently heating the wood boiler (the outdoors) with oil after the wood fire goes out.
 
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You said "we just installed"
Who installed this? you or a "pro"heating guy?

Do you know the water temperature coming in from your outside wood boiler ?

Looks like you need to control the oil boiler with an aquastat "make on temperature drop".
When water in the oil boiler drops below a certain temperature it needs to come on; when there is a heat call form the house of course

Also, the green Taco circulator is wired into the oil aqastat, so it's kind of normal that the oil boiler will come on.
 
On my oil burner I changed the wiring in the emergency switch that's on the oil furnace so with the switch off everything works except the oil burner. To get the oil burner to work have to turn on the switch, otherwise it doesn't come on at all. If you're looking for back up from oil that wouldn't work. Probably not the correct way to do it but ours has been like that for several years with no issues.
How's your boiler working out for you? A friend of mine just installed one of those and seems very happy with it.
 
When I say we I mean me and my wife (just because she lives here, too). Ill try to attach more pictures but it seems very just need to add an aquastat. This is the back of wood boiler and inside of house at heat exchanger. Makes sense that I need something to tell oil boiler not to fire.

Pettibone - I like it so far. Burns clean and efficient. Just been frustrating for me setting it up and listening to oil boiler kick on.

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OK, is there no direction from Crown Royal on how to do this.
I'm sure they have done this before.
 
I just wired a simple switch into the wire going to my burner. You have to remember to turn it off when burning wood and on again when you're not though.
 
I am stepping out of this as its an OWB. I expect OWB people have their own favorite methods.
 
The simple answer to my problem was to stop using my indoor woodstove. This is going to be hard to do but my wife already likes less of a mess. I shut my woodstove (inside) yesterday, oil boiler has not kicked on since.
 
So adding even more heat makes the oil boiler come on? Guess I'm confused about that, not that I'm any expert on heating systems.
I am guessing its because of an improper or inadequate install. From looking at the pics, the OWB would only heat the IWB when the zones are circulating. And if say only 1 zone was circulating, not a lot of heat gets transferred. So if you have a stove going that prevents IWB zone heating because thermostats are satisfied, the IWB doesn't get very hot from the OWB.
 
I am guessing its because of an improper or inadequate install. From looking at the pics, the OWB would only heat the IWB when the zones are circulating. And if say only 1 zone was circulating, not a lot of heat gets transferred. So if you have a stove going that prevents IWB zone heating because thermostats are satisfied, the IWB doesn't get very hot from the OWB.
Yes, exactly. Overnight our IWB did not kick on, assuming because there was enough call for heat it kept the boiler satisfied. During the day today it has kicked on twice, I am assuming because its warm out and there is not a call for heat and boiler is not satisfied. I can jump out the TT terminals on the control or aquastat (box by oil burner motor) that turns the return circ pump on in without firing boiler. I need a way to have the oil boiler not fire and keep that return circ pump going.
 
On my system i have a aquastat on the feed to my heat ex changer that control's the backup boiler.
When the temp coming from my wood boiler/storage drops below 100 F the aquastat switches power from the pump that supplies the heat exchanger, to my oil fired boiler.At that time my wood boiler and storage don't come into play till i start a fire and the wood boiler starts to produce heated water to send to the heat ex changer and storage.
 
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I have my aquastat on boiler turned down to 145/125 right now. I am going to try putting a strap on aquastat on the supply to oil boiler and hook that into TT terminals and set aquastat 10 degrees or so higher than boiler. I am hoping that kicks circ on and not fire oil boiler. Something cheap to try. In theory this all seems so simple, I am just not mechanically inclined in this area. Good learning experience I guess.
 
There very well may be a simpler solution here, but it sure seems to me like a simple PID temp controller and an inexpensive thermocouple mounted in the right spot would fix this... @sloeffle ?
 
I have my aquastat on boiler turned down to 145/125 right now. I am going to try putting a strap on aquastat on the supply to oil boiler and hook that into TT terminals and set aquastat 10 degrees or so higher than boiler. I am hoping that kicks circ on and not fire oil boiler. Something cheap to try. In theory this all seems so simple, I am just not mechanically inclined in this area. Good learning experience I guess.
I might try lowering your low all the way, and your diff to 10.
 
There very well may be a simpler solution here, but it sure seems to me like a simple PID temp controller and an inexpensive thermocouple mounted in the right spot would fix this... @sloeffle ?
Yep, you could use a PID controller to do that, or a Ranco. There’s a good video on YouTube on how to setup a Ranco to do exactly what you are wanting.
 
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I have my aquastat on boiler turned down to 145/125 right now. I am going to try putting a strap on aquastat on the supply to oil boiler and hook that into TT terminals and set aquastat 10 degrees or so higher than boiler. I am hoping that kicks circ on and not fire oil boiler. Something cheap to try. In theory this all seems so simple, I am just not mechanically inclined in this area. Good learning experience I guess.
I’m assuming what kind ( oil, NG, wood, etc ) of boiler it is doesn’t really matter, but I’d be hesitant on setting it that low. Anything under 140 will cause the boiler to sweat when it’s running. This could possibly lead to premature corrosion.