OWB not transfering heat into oil burner

[Mahoney86]

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?

 

[Sodbuster]

Bump

 

[E Yoder]

Some pictures would help. How does the oil boiler read 7 psi plumbed directly into an open vented outdoor furnace? Something's weird. I would normally separate the pressurized oil boiler from the open outdoor system with a flat plate. But... It should still work, just be harder to get air out, possibly.
Are the lines coming in from the OWB completely purged of air? If the OWB is lower than the house opening a purge valve/ air bleeder could suck air in.

 

[Mahoney86]

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

 

[maple1]

Tieing an OWB directly to an indoor system like that is something I would most definitely avoid.

Indoor systems are usually designed to operate with a certain system pressure. Take that pressure away and you can get circulators cavitating and air locking and water not getting as high as it needs to. Plus you've introduced a whole pile of fresh oxygen to the whole indoor system which brings corrosion potential with it.

This is almost certainly a trapped air problem. One which would be hard to chase from here, without being there in person.

Just on the 3 pics - are there bleed points in the highest points of those blue & red pipes in the second pic?

Sometimes air can be forced out of piping by hooking up a hose to a low spot in that piping, with DHW pressure on it, and forcing it through & out a high spot.

There could also be a problem with the basic layout of the whole thing. Like, elevation differences all around that would make flowing the water in an open system very hard to do. We don't know much about the whole basic layout. Also hard to get a head around your entire plumbing layout - complete pics and/or a drawing might help. But likely won't substitute for being there.

 

[stee6043]

Is your outdoor boiler physically higher than all of your basboard units?

 

[Mahoney86]

The wood boiler is not higher than the baseboard units

 

[maple1]

I can't see this setup working well at all without a heat exchanger between systems. Even a closed pressurized system can have difficulty if you don't keep enough pressure in it.

 

[stee6043]

The wood boiler is not higher than the baseboard units

I think you're going to have some substantial problems with this setup. Anytime your circ pump is not running your baseboards will drain if the boiler is below the baseboards. When the circ pump turns back on you'll get massive air lock.

I think you're in a no-win situation right now. Get the flat plate ASAP.

 

[TCaldwell]

This system should work, based on the principle of putting a finger over a straw to hold water as you pull it out of the container, if there are no air leaks, ie can vents higher than the water level in the outdoor boiler, and you have removed the extrol expansion tank for the oil boiler.
I do agree the system is probably airbound as purging is more difficult in a unpressurized system, and water quality issues need to be monitored frequently to avoid physical damage to components.
The benefits are 1 less circ and no temp loss through a hx.

 

[Mahoney86]

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

 

[warno]

To run a FPHX you would simply tie your oil boiler into one side of it and the wood boiler into the other. Make sure you have an opposing flow between the 2 sides. You could very easily install one based on your pictures. You could then pressurize the oil boiler side and leave the wood boiler side as an open system and I think you'll be pretty happy.

 

[E Yoder]

A couple additional thoughts-

Hot from the OWB should be entering at the relief valve tee to send the hottest water out to the baseboards. Blue should be to the lower tee on the return. Right now water temps are mixing in the boiler.
As was mentioned the baseboards will not drain provided no air vents are open, they just run in a slight vacuum.
In the pics the ball valves are all closed, I'm assuming the two at the boiler tees would normally be open, the crossover stays closed? Sounds obvious, but I've seen about everything.
The same tees could be used with a flat plate, but you should pump out of the drain, returning hot into the top. Counterflowing through the flat plate.

 

[maple1]

Don't think those high spots in the red & blue, between the basement wall & the oil boiler, were addressed.

If you really want to make this work at all no matter what route you take, you really need a spot in those two high spots to get the air to bleed out of. So I would start there. Cut in bleed valves. That might be all it would take to get the existing setup to get some heat going. The setup still might be problematic, but the cost of doing that little bit will be cheap & easy & will be needed regardless.

 

[Mahoney86]

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]

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.

 

[Mahoney86]

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.

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)

 

[Mahoney86]

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.

 

[warno]

To plumb in your flat plate HX it requires counter flow internally. So just think about it as both your "cold" lines go on one side and both your "hot" lines go on the other.

"Cold" lines being your OWB return and oil boiler supply to HX.

"Hot" lines being your OWB supply and your return to oil boiler.

You will need a circ on both sides to push water through both sides. And try your best to keep the HX as vertical as possible.

To the others replying here please correct me if any of this is wrong.

 

[Mahoney86]

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

 

[maple1]

So it sounds like OWB flow isn't making a loop into the house & back again - at all? Or am I misunderstanding something? Did you follow the heat from the OWB & see where it goes?

Just from that, it sounds like there are other issues of some kind going on that should be sorted before you try adding a HX. If the OWB water isn't at least making a loop into the house & back again, that's 3 strikes all at once.

 

[Mahoney86]

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

 

[maple1]

Was the oil boiler circ running when you tried that? Did you try it with it both off & on?

A couple better pics might help. Still not sure how things are flowing here.

Which way does that oil circ flow when it is running? Down or up?

 

[Mahoney86]

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.

 

[maple1]

If you get a free flow into the house and back again thru that short line that bypasses the oil boiler, then close that ball valve and open the other two, I am failing to see why it wouldn't work it's way through the oil side. With all that's posted.