OWB not transfering heat into oil burner

I have a newly acquired Central Boiler 1450 outdoor wood boiler. 75' run of 1" thermos pex placed 2 feet underground and then down into my basement Crown oil furnace. My 1800 sq ft home is all on 1 zone baseboard heat (basement is not heated)

I do not have a wood boiler dealer near me so I have been speaking with dealer out of state where I have purchased some products from. I also looked at the install of the dealers furnace and mimicked the same install.

My OWB supply is piped into the oil boiler supply inlet (after the pressure tank and circulator pump). The system returns through a T installed before the oil burner pressure relief valve and back to the wood boiler. The intent here was to keep the oil burner constantly not.

My wood boiler is set at a max temp of 195 with a differential of 10 degrees. I can get to 195 relatively quickly at the wood boiler and I will then open up my valves inside the house for the wood boiler water to circulate into the oil burner. Oil burner temps are set to 160 high and 140 low.

I filled the OWB through from the oil burner domestic water side as well as checked all purge valves on the wood boiler side for air. I also ran my baseboards up to pressure and opened up the air bleeder valves one by one to ensure no air in my system.

My supply from the OWB is hot but I can keep my hands on the pipe for 5 seconds, with a cheap infrared temp meets the pipes are no hotter than 160 even when the OWB is at hi temp mode (200 degrees). The temp gauge on my oil burner reads no higher than 160 as well and the oil burner will still run to maintain that. I’ve even tried turning the oil burner to 140 and the temperature will continue to drop.

My water condition has a pink dye in it which I can see if I purge any of the drains at my oil burner. Though when I purged my baseboards I only saw clear water.

Lastly my OWB continues to smolder and then eventually throw a fire out cold because the system is not getting cooled water requiring the OWB to fire. The only way I’ve been keeping a fire for a day is by lowering the fan pulse mode to every 20 minutes for 60 seconds. Then in which the boiler will go into hi temp mode

I have cranked the heat to 70 ( we normally keep the house at 59 during the day and 64 at night due to the oil bills. Have taken long hot showers only to loose hot water ( my oil boiler heats my domestic hot as well.

My dealer suggested maybe since it was a used unit to change the circulator pump. I did that and still cannot seem to get things circulating in my base boards. If I open the purge valve on my OWB supply ( right at the entry into my oil burner ) I get very good water flow and after a few seconds the water starts to steam and I can feel the pex lines really begin to heat up on the supply. My pressure gauge on my oil burner reads 7psi and I have no circulator issues if when I’m hearing with just the oil burner.

Im really lost at this point. Any thing I should be looking for next?

Here a few quick images. In the last photo I T’ed the OWB lines into a loop bypassing the oil burner so I can keep the circulator running if I am out of town for the weekend etc...

I was also a bit confused how I had 7psi in my oil burner with an open pressure system tied in, I was assuming it was head pressure from my OWB being at ground level and my oil burner being approximately 6-7’ lower than the OWB.

I’m not opposed to a flat plate as I originally had planned on ordering one. Though after speaking with the dealer that we would only be in this home for another 2 or so years ( planning on moving and upgrading house size) it would likely be an unneeded expense at the moment and I would be fine plumbing directly into the oil burner

The wood boiler is not higher than the baseboard units

If I go with a flat plate, what size is recommended? I see a bunch I can get on Amazon Prime.

Also I would like to do as little modification to my current piping, any recommendations on the install layout of the flat plate? Can I plumb the oil burner side to the flat plate exactly as I have it now and then just plumb the OWB supply and return to the flat plate. Would I need any additional pumps?

With the flat plate how do I heat my internal domestic hot water? I thought this was the whole reason of having the OWB flow through the oil burner

Will I still be heating my domestic water when I have the plate exchanger on?

In regards to the high point on the pex lines, figured that may be part of the issue. If I’m going to cut the lines to add another T and a drain valve, I could really just do some slight rerouting and keep the lines down low by running them horizontally . I only ran them up hi to have a little cleaner look in the boiler room

E Yoder said:

You said the oil boiler heats your domestic water, correct? Then if you heat the oil boiler it should heat the domestic water.
The high points may be air locked as was mentioned. Teeing in domestic water pressure with a ball valve would allow you to purge supply and return in seconds. Then the high point should be fine.

Click to expand...

Yes oil burner heats my domestic water.

See i have purged the supply and return lines of the OWB with domestic water a few times now so I would be amazed if I have any air locks at those high points ( I guess anything is possible though)

Ok, I ordered a flat plate heat exchanger last night and it will be here today (good ole Amazon Prime!) Last night I got into the crawl space and removed that High spot on the supply and return to the wood boiler now I have a straight horizontal run and then down into my oil burner.

I fired up the wood boiler just to see if it would circulate water. In bypass mode I read 163 on both the supply and the return while in bypass. I turned down the high and lows on the oil burner and opened up the valves from the OWB. Eventually the OWB went into hi temp mode, the oil burner never went above 160 despite the temperature of the OWB lines being in the the mid 180s per my cheap infrared thermometer. All of the cast iron pipe into the boiler was 185-190. The OWB return line was at 130* and all of my baseboard pipes would not read anything more than 80* with just the OWB. I was hopefull it would maybe settle in as the temp gauge on the oil burner eventually got to about 170 after a few hours of the OWB going. I woke up at 530am this morning to the oil burner running (hi and low temps were set to 140) and a Fire Out code on my OWB.

So needless to say removing the high points and rebleeding my lines didn't help. Its definitely not worth the headache trying to make this work so I am happy I have the flat plate HX coming today.

Can someone guide me on how to install the HX? I know once side gets the wood boiler return and the wood boiler supply, though how do I plumb the oil burner side? Am I just taking the blue return pex line coming out the back of my oil burner into one side and then the red supply at the bottom of the oil burner into the opposite side of the plate exchanger? Looking at some videos online it looks like many people are just putting the plate exchanger inline of the oil/propone boiler supply and not even touching the return.

I would like to leave as much as my plumbing in place as it is, unless of course I need to modify it.

But will a setup as shown in the attached mark up work? Sorry it is a crude sketch

The heated from the OWB will make a loop when I have that bypass valve open and no water going to the oil burner.

It does not appear to be making a loop when I send water through the oil burner

Yes circ was both running and not running. Cranked the heat up to 68.

I will get some pictures tonight. The oil circus flows down to where my pex tie in is and then elbows back into the boiler.

If i open any of my purge valves water definitely flows out well.