Pressure loss questions...Yes Im a NOOOOOB

[mfoster]

Howdy all. Wife and I just purchased a large home in Upstate NY about 6 months ago.

Heating is complicated...or at least to me.

We have a Thermo Control large wood boiler in the garage. Pex underground to a tank in the basement. Tank connects to a water holding system with hot water inside. That all connects to a Mcclain Oil boiler system. Hot water then moves to the hot air circulator.

Our problems began the first time I started the wood boiler to test it all out. I warmed the unit to 175 or so and turned on the water circulators for the "loop"? and it seemed to be working for the day. This was in October, and we really did not need the wood, so let the wood go down, and turned off the circulators. Well the wood was not all the way down, do the furnace heated to at least 220. Pressure rose to 30ish...but temps were still rising to over 240, so I freaked and turned on the circulators in hope to even out temps. It wasn't dropping quick so we opened a water valve and let out some steam/water/pressure into the basement. BIG MESS.

We did not know either way if this caused damage...it was making some serious pipe clanking noises on the thermo control boiler. No leaking water so we figured all ok.

Fast forward, running since Nov 15th or so. We see pressures drop to 0 if boiler temp is below 140, then rise to 15 if boiler temp is 165 or so. Issues are, we are not able to maintain a temp of 160 to 170 so our oil is kicking on constantly and I am wondering if we are wasting our wood even using the outdoor boiler rather than the oil boiler as primary.

My questions...

Is it possible that I have an underground pex line cracked that is causing loss in pressure? I am not really seeing any evidence outside. We do have some ground water in a gravel portion of our basement. (house built in 1900) water is not rising and does not seem excessive for what we saw upon move in.

Does this issue with temps not rising sound like I have unseasoned junk wood?

Should my furnace door have a fan or anything on it. I have a cut off attached to it with a temp controller. No fan is present.

Did I purge out pressure when I let water out when we were worried about overheating. Would recharging the tank fix this, or would pressure just drop again since its rising and falling daily depending on boiler temps?

OK, sorry for the long first post. I have been evaluating my system for a couple weeks and wanted to get all my questions in order before I posted.

Thanks all. Hope to hear your thoughts. I can supply some more info if directed.

 

[velvetfoot]

I'm no expert, but I can't visualize your system. Maybe someone else can.
I think you should sketch out the system and post a picture of it.

"We have a Thermo Control large wood boiler in the garage. Pex underground to a tank in the basement. Tank connects to a water holding system with hot water inside. That all connects to a Mcclain Oil boiler system. Hot water then moves to the hot air circulator."

It's hard for me to figure out what that means.

 

[mfoster]

I'm no expert, but I can't visualize your system. Maybe someone else can.
I think you should sketch out the system and post a picture of it.

"We have a Thermo Control large wood boiler in the garage. Pex underground to a tank in the basement. Tank connects to a water holding system with hot water inside. That all connects to a Mcclain Oil boiler system. Hot water then moves to the hot air circulator."

It's hard for me to figure out what that means.

I can see what you mean.

I can work on a drawing...

In the mean time. Part of our loop is a tank approx. 30 gallons. That tank then has a pipe to the mcclain oil furnace. The mcclain has a pipe to a central water tank, that has the potable water run through it for hot water. Also branched from the mcclain system, is the line to the hot air circulator for the home (I cant remember the name for this thing.)

 

[velvetfoot]

Again, I'm no expert, but going through this could get tedious.

Starting with:
We have a Thermo Control large wood boiler in the garage. Pex underground to a tank in the basement. Tank connects to a water holding system with hot water inside. That all connects to a Mcclain Oil boiler system. Hot water then moves to the hot air circulator.
and
Part of our loop is a tank approx. 30 gallons. That tank then has a pipe to the mcclain oil furnace. The mcclain has a pipe to a central water tank, that has the potable water run through it for hot water. Also branched from the mcclain system, is the line to the hot air circulator for the home (I cant remember the name for this thing.)

Question: How many tanks are there, and how big are they?

 

[jebatty]

I agree with the vagueness of your post. I note this from the Thermo Control website: "The boiler models are closed system (pressure vessel) units. They have inlet and outlet fittings and are designed for 12-15 PSI operation." I assume your "Mcclain Oil boiler" and your system also is a closed, pressurized system. Going from 0 to 15 psi sounds like an expansion take issue. If you have a two story house, the cold water, static pressure of your system at the system low point should be about 10-12 psi, and then the psi will rise as the water temperature rises, reaching a maximum of 15 psi at the Thermo Control (according to Thermo Control). To do this you need adequate expansion take sizing to accept the expanding water volume while staying within the operating limits of your system.

 

[stee6043]

One quick thought - if your system pressure is 0 when idle/cool your circs likely aren't going to work well. I'd first suggest you isolate the wood boiler system from the gas boiler with whatever valves you may have. Then add water to the wood side (I assume you have a fill valve someplace otherwise you need to hook up a garden hose). Bring the system pressure back up to 12-15psi cold and let is sit for several hours. Confirm there are no leaks. Then start again.

My two cents only.

 

[velvetfoot]

I mean, is there an autofill valve? Is the 30 gal tank described for expansion? What's a "central water tank"? What's a 'large' wood boiler? etc

 

[stee6043]

The easiest way to satisfy the boiler room is to POST MANY PICTURES. Save yourself the time of drawing things. We're a very visual group here...

 

[mfoster]

Thanks for all the replies. I'll head out for pictures now.

 

[maple1]

Pictures of everything are needed.

Some random things:

-Using the wood boiler should not require manual circulator operation. It should start on its own when the boiler is up to temp, and stop on its own when it drops. You made a big mistake turning off the circulator while there was a fire going in the boiler - the circulator is needed to move heat away from the boiler.

-You let pressure out of the system when you blew it off. That should not have been necessary - there should be a relief valve on the boiler that does that when it is necessary, on its own. So either there is a valve & it isn't working, or there is no valve & there should be, or you didn't need to do what you did.

-Along with that relief valve, there should also be a fresh feed inlet from the water supply, that will let in fresh water to maintain a minimum pressure (and would have let cold water in when you blew it off). Sounds like that is either not in place, or valved off, or not working right. You should not see 0 pressure at any time.

-You should not see a 0 to 15 psi pressure rise with only a 140 to 160 temp increase. I suspect either a ruptured bladder in your expansion tank, or else you have a bladderless expansion tank and it is water logged & needs draining/repressurized.

-If the pressure stays constant at a constant temperature, you shouldn't have any leaks, underground or anywhere else. Unless the fresh feed is constantly letting in water to maintain a constant pressure from water lost somewhere else. But as noted above, your fresh feed is an uncertainty. Typically, to determine a leakage or not, one would pressurize the system to a certain normal operation pressure, keep the system at a more or less constant temperature, then valve off the fresh feed inlet & see if pressures drop. In your case, that should be done with no wood fire going just in case pressures do drop out.

-Green wood can have problems getting water hot enough. But you need to verify your system is OK first.

-A gravity dump zone should be in place to dump heat from the wood boiler in the event of a power outage. That should have covered you in the overheat situation. Sounds like there isn't one in place.

 

[mfoster]

 

[jebatty]

I see one expansion tank behind the stack of the Thermo Control. Based on the picture it looks like you may have the Model 3000 Thermo Control, and the specs for that boiler show a water capacity of 300 gallons. Total system water then would include the oil boiler, all piping and emitters. It appears to me that the one expansion tank shown likely is considerably undersized for your application.

 

[mfoster]

I see one expansion tank behind the stack of the Thermo Control. Based on the picture it looks like you may have the Model 3000 Thermo Control, and the specs for that boiler show a water capacity of 300 gallons. Total system water then would include the oil boiler, all piping and emitters. It appears to me that the one expansion tank shown likely is considerably undersized for your application.

what would the tank in the basement to the left be called? Also, the expansion tank on the top of the Thermo control unit, should I try to add pressure to it. It looks to have a air stem at the top. I was told I can add pressure through that.

 

[mfoster]

The easiest way to satisfy the boiler room is to POST MANY PICTURES. Save yourself the time of drawing things. We're a very visual group here...

I added some, I can add more of specifics if needed.

 

[mfoster]

I mean, is there an autofill valve? Is the 30 gal tank described for expansion? What's a "central water tank"? What's a 'large' wood boiler? etc

I'm hoping some of the photos will answer some of this. I think there is an auto fill valve above/behind the piping for the oil furnace shown in the basement. I will grab a specific photo for that.

 

[maple1]

To add to jebatty, that is a pretty sketchy looking smoke pipe out the top of the wood unit. Is that double wall with the outside wall all corroded away?

Also wondering that the gizmo is on the side of it.

That's a pretty crudded up looking what I think is an air vent, just below the expansion tank.

Don't see a relief valve in the pics.

Can't tell about or see fresh feed stuff.

No dumping capabilities seen.

The pressure/temp guage looks kind of old - may or may not be accurate. The more of those things in a system though, the better.

That's just general stuff - and having said all of it, you might be OK pressuring the system up a bit & running. But I think I would get someone in who knows their stuff to give it a good look over first - especially with what you said the pressures were doing. You may or may not have issues losing heat via the underground piping also even if it's not leaking - a different fish kettle.

EDIT : One thing you could do real quick, is check the air valve on top of the expansion tank. It's under that little blue thingy, looks like an ordinary tire valve. If you push it in a little the same way you would let some air out of a tire, and water comes out - you know you have a bad bladder. For a more thorough check, you would let all the air out to make sure you get no water, then pump it back up with air to the 8-10psi or so range. If you have an accurate air pressure (tire) guage, and an air pump.

 

[mfoster]

To add to jebatty, that is a pretty sketchy looking smoke pipe out the top of the wood unit. Is that double wall with the outside wall all corroded away?

Also wondering that the gizmo is on the side of it.

That's a pretty crudded up looking what I think is an air vent, just below the expansion tank.

Don't see a relief valve in the pics.

Can't tell about or see fresh feed stuff.

No dumping capabilities seen.

The pressure/temp guage looks kind of old - may or may not be accurate. The more of those things in a system though, the better.

That's just general stuff - and having said all of it, you might be OK pressuring the system up a bit & running. But I think I would get someone in who knows their stuff to give it a good look over first - especially with what you said the pressures were doing. You may or may not have issues losing heat via the underground piping also even if it's not leaking - a different fish kettle.

That chimney was our first concern. As it turns out it is super heavy black steel pipe. It has lots of life left in it. Not typical chimney use, but I was told its actually above and beyond what would be used. Our home inspector gave it the OK. The thing on the side of it is another temp guage that will shut damper if it gets to hot.

"That's a pretty crudded up looking what I think is an air vent, just below the expansion tank."
I was under the impression that was a Blow off or relief valve. I have heard that thing hissing at times. Not necessarily when temps or pressure was high. Can this unit be causing my issues?

As for dumping, I don't see anything on this unit. I opened a line/valve near the large tank in the basement when we wanted to release some hot water when we were having our issue the first time we used it.

Fresh feed has me confused...I think that it autofills from the lines in the basement after the water moves through the oil furnace. I was told the one unit in the line behind it is an auto fill valve. Question with that would be, if filling when needed wouldn't it gain or hold pressure?

 

[maple1]

"That's a pretty crudded up looking what I think is an air vent, just below the expansion tank."
I was under the impression that was a Blow off or relief valve. I have heard that thing hissing at times. Not necessarily when temps or pressure was high. Can this unit be causing my issues?

Looks like an air vent. It shouldn't really hiss much, unless you have air coming in somewhere else. But if the system pressure drops out, it could also let air in. Don't think it's causing your issues, but all the crud isn't good. And they're cheap. Blow off valve should be on the top of the boiler itself. We can't see the whole top - is there anything else up there? If not, that would be a concern.

As for dumping, I don't see anything on this unit. I opened a line/valve near the large tank in the basement when we wanted to release some hot water when we were having our issue the first time we used it.

That is something I would likely look into having added, for sure. If power goes out with a fire going, your pumps stop pumping. That's a big boiler, even if the damper closes like it's supposed to, temps will climb. If the damper hangs up or doesn't quite close due to a piece of dirt or whatever, that could be really bad news. Also, if the damper sticks or hangs up during normal operation, you could also be in need of a dump zone. Redundancy is a good thing to have.

Fresh feed has me confused...I think that it autofills from the lines in the basement after the water moves through the oil furnace. I was told the one unit in the line behind it is an auto fill valve. Question with that would be, if filling when needed wouldn't it gain or hold pressure?

Part of a fresh feed setup is a pressure regulator. (Should also be a backflow preventer too). The regulator limits the pressure of the system. Usually set for 12 psi (but usually adjustable), it won't feed any water in until psi gets below 12 (or whatever it is adjusted to). If it's working properly. Sometimes the get dirty & will let in water when not supposed to. A good picture of that area should show.

 

[mfoster]

"That's a pretty crudded up looking what I think is an air vent, just below the expansion tank."
I was under the impression that was a Blow off or relief valve. I have heard that thing hissing at times. Not necessarily when temps or pressure was high. Can this unit be causing my issues?

Looks like an air vent. It shouldn't really hiss much, unless you have air coming in somewhere else. But if the system pressure drops out, it could also let air in. Don't think it's causing your issues, but all the crud isn't good. And they're cheap. Blow off valve should be on the top of the boiler itself. We can't see the whole top - is there anything else up there? If not, that would be a concern.

To the rear corner more of the boiler there is another small unit coming out of the top. Its visible in this photo inbetween the chimney and water outlet view. Is that a pressure relief valve?

 

[maple1]

Doesn't look like one I've ever seen - not sure what that is, from the pic.

 

[velvetfoot]

I'd say, take some more pictures. Close ups, different angle, from behind wall, etc.

 

[velvetfoot]

It seems you have to add pressure and maybe bleed the lines so there's no air? I don't see an air separator. Did the pumps make a lot of noise when they run?

 

[mfoster]

It seems you have to add pressure and maybe bleed the lines so there's no air? I don't see an air separator. Did the pumps make a lot of noise when they run?

Do you mean my circulator for the loop? Well here is the crazy thing, for some reason that circulator runs 24hrs unless I turn the entire Wood element off. As for noise...no very quiet.

 

[Fred61]

Getting away from the mechanics of things. Although I don' have my head wrapped around this, one thing that is concerning is that you mentioned was clanking during the over heat episode. That clanking indicates you made steam. If the steam was the result of the wood boiler overheating, you could have smoked the underground pex since it will not handle those temperatures.

 

[mfoster]

Getting away from the mechanics of things. Although I don' have my head wrapped around this, one thing that is concerning is that you mentioned was clanking during the over heat episode. That clanking indicates you made steam. If the steam was the result of the wood boiler overheating, you could have smoked the underground pex since it will not handle those temperatures.

Fred that was a major concern of mine. My pex is rated at 180. Would I hold pressure at all with a broke line? Today having the day off I've been feeding the wood and holding at 12 to 20 depending on temps.