OWB not transfering heat into oil burner

[Dutchie84]

Maple beat me too it


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[TCaldwell]

The reason I ask about the isolating the expansion tank is that it was recommended to me, as I’m non pressurized as well.

 

[maple1]

The reason I ask about the isolating the expansion tank is that it was recommended to me, as I’m non pressurized as well.

Is your whole system non-pressurized?

This one has an HX in place now. I think. So expansion tank should still be at play, on the oil/pressurized side.

 

[Mahoney86]

The expansion tank is still in place as the indoor system is still pressurized. My OWB is a complete separate open system due to the addition of the HX.

Maple, the little blue bypass leg is there so that when the OWB is not in use (away for a long weekend) I can close off the flow going through the HX so that I am not wasting oil heat maintaining the boiler temperature.

 

[TCaldwell]

Maybe I’m missing something, but looking back at the pictures I don’t see a circ moving the heat out of the flat plate to the set of closely spaced t’s and back to the flat-plate?

 

[Eureka]

It’s relying on the oil boiler circulator to push the return water through the plate exchanger on a thermostat call for heat. Kind of why I don’t see this working well to preheat the oil boiler because there’s nothing keeping heat transfer going when the thermostat is satisfied.

 

[TCaldwell]

I believe that’s the problem, the closely spaced t’s I believe should be on the return to the oil boiler with a circ between the flat plate and closely spaced t’s that is powered the same as the unpressurized owb circ?

 

[maple1]

But the primary problem right now - I think (this thread has gone in a few circles) - is that the heat isn't getting from the OWB to the flat plate to start with.

As far as we know.

That should not be a problem if that loop is flowing at 9gpm.

Yes, I think the oil side of the HX could be done better. But getting past that first issue has been hard to do. For some reason.

IMO either the GPM measuring exercise, or the temp measuring exercise, isn't accurate. Or there is some other problem in the one simple loop that hasn't been made apparent yet.

 

[Dutchie84]

Like Maple said, was the bypass open when you did your flow test?


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[Eureka]

I agree @maple1
From the info we have, it appears OP is losing around 29 degrees to the ground, at 9 GPM. I stand by my suspicion of inaccurate temp readings being a contributing factor here. If it is indeed Thermopex, that’s impossible unless the installation was seriously compromised and the outer casing and foam are missing in a large area.

 

[TCaldwell]

I thought with posts 149/150 flow estimated to be 9gpm, even at 6.6 a low calculation round trip from the owb through the flat plate and back to the return port of the owb, wouldn’t explain his problem. But what would explain is if there was poor flowthrough the pressurized side of the flat plate, relying on zone flow circs to make that happen.

 

[Mahoney86]

The Bypass was not open during the flow test. Everything was kept normal to allow for full flow through the HX.

Can someone steer me in the right direction of what I should be doing plumbing wise on my oil boiler return? It was my understanding on this thread that I should have done exactly what I did but Teeing off the HWBB return and T back into the return on my Oil Boiler.

I would agree with the statements that my Oil Boiler is not staying hot and it turns on all of the time. I would agree this thread is going in many many directions, but I have tried my best to take peoples advice here and install as told. If I installed something incorrectly let me know I will make modifications.

I stopped using the infrared gun to take heat readings. I am now using my BBQ Thermopen and measuring the actual water temperature

 

[maple1]

I thought with posts 149/150 flow estimated to be 9gpm, even at 6.6 a low calculation round trip from the owb through the flat plate and back to the return port of the owb, wouldn’t explain his problem. But what would explain is if there was poor flowthrough the pressurized side of the flat plate, relying on zone flow circs to make that happen.

That wouldn't explain the big temp drop though from the OWB to the HX? It should only be a couple or very few degrees - he's got 20.

 

[maple1]

I am now using my BBQ Thermopen and measuring the actual water temperature


How are you able to get that into the water?

 

[maple1]

Can someone steer me in the right direction of what I should be doing plumbing wise on my oil boiler return? It was my understanding on this thread that I should have done exactly what I did but Teeing off the HWBB return and T back into the return on my Oil Boiler.

I think that was suggested as the easiest way. And it should work. But it would depend on how steady your oil boiler & heating zones circulate. Since the HX won't transfer anything when the oil side isn't circulating.

And it would also depend on the ability of your HX. Which IMO is undersized (I would use one 4x the size). And it is also not oriented properly.

 

[TCaldwell]

I understand your frustration and appreciate your patience, can we all agree on a flow rate of 6.6 to 9 gpm round trip on the owb side? Maples concern of a 20 degree drop round trip with no load should be the next to beat to death.
Can you shut off all loads and isolate the owb loop and let run for 20 minutes or so and measure temps at outlet from owb and return at owb. That should give a good sense of temp change on that loop, if good we can move on if not it’s probably a hx issue.
I agree with maple the hx orientation isn’t right

 

[warno]

If you are flowing 9 gpm, 5 gallon bucket - 30ish seconds, there shouldn't be this big of problem to get heat from the OWB to the oil boiler through the FPHX. other than the HX itself is limiting it a 20 plate is honestly small for what you are doing. But the large delta T on the OWB side is telling me there isn't quite that much flow.

When you did the bucket test did you have the circ running with the return line on the outside of the bucket then move it into the bucket right when m toy started the timer? Because I believe you mentioned the amount of water pushing out of the line was alot. I'm wondering if you maybe started filling off of the gravity in the water jacket before starting the circ.

Another thing I'm wondering, and maybe someone smarter than me can say yes or no, if you open the return line on an open system it's going to start "draining" the boiler. Could it be possible the water level would push past the circ and give a higher flow rate than what is happening while the circ is running?

 

[Mahoney86]

When I did the flow test I plugged the pump in without a bucket underneath and then as it was flowing moved the bucket into the flow path of the OWB return water.

When I get home this evening, I will fire up the boiler again ( we all know that it is out again since this thing is getting no load) and bring up to temp. I will then be sure my oil boiler is off and I will open the purge valves at the HX and take temp readings of the actual water with the thermo pen.

 

[Mahoney86]

OWB is up to temp and currently at 200* on display

Inside temp of the actual water ( coming out of the purge valve on both. The supply and the return are both measuring 187* with no load on the indoor system at this time.

 

[TCaldwell]

How long did it take to get to 187, if you let it run longer does the temp rise at all? The fact that both are the same temp is a good sign. Could it be possible the sensor for the boiler display is located higher than where you are taking the purge valve temp?

 

[maple1]

OWB is up to temp and currently at 200* on display

Inside temp of the actual water ( coming out of the purge valve on both. The supply and the return are both measuring 187* with no load on the indoor system at this time.

That is a different outcome than we previously saw. Time to move focus to the other side of the HX, I think. Get it opened up and running and measure temps again.

 

[warno]

I agree with @TCaldwell. The temp probe on the OWB is probably in the water jacket higher than the supply port. It doesn't take much to height to make a difference. I would say you need to try circulating the oil boiler water through the FPHX continuously as long as the OWB is running. Maybe it's just not putting the heat into the boiler often enough because it's only circulating with thermostat call.

 

[maple1]

I agree with @TCaldwell. The temp probe on the OWB is probably in the water jacket higher than the supply port. It doesn't take much to height to make a difference. I would say you need to try circulating the oil boiler water through the FPHX continuously as long as the OWB is running. Maybe it's just not putting the heat into the boiler often enough because it's only circulating with thermostat call.

I think the main issue, if we do indeed have OWB water running well thru the HX, is the HX is too small.

 

[TCaldwell]

 

[TCaldwell]

Sorry the above pic is not very clear, but I believe this concept would work