# omg now what am i going to do?

### Re: omg now what am i going to do?

ALuminum PEX is usually used to increase heat transfer via conduction of the pipe walls to an outside material, often aluminum under floor plates. The pipe sits in channels in the aluminum plate and the plate is fastened to the bottom of the wooden floor to be heated.

The plate helps spread the heat out over the floor to be more uniform and radiate more heat from the tubing.

AL-PEX is more expensive and I don't of anyone personally who has used it for anything else. Typically you do not want the walls of the PEX to conduct heat unless it is infloor or an installation like mentioned above. When used as a transport medium, it isn't desirable for conduction, though copper and iron do as well.

Which relates to the other part of your question- what size to use?

First a quick visual explanation about how water in a tube behaves with heat. When in a tube, liquid (and to some extent gases) behave very differently than in open space. Think of how air moves over the top curved surface of an airplane wing. If you were to freeze time and mark the air particles in a vertical line, perpendicular to the wing, before the air reaches the wing, then skip ahead until the particles reach the other side of the wing, you would see (in a perfect situation) the particles all are lined up vertically again.

If you rewind just a bit to when the particles are encountering the wing, you will see those marked particles are still in a line, although the ones on the top aren't traveling horizontally in a straight line, they have to travel over the curved surface of the wing. Since a straight line is the shortest distance between two point, the curved path has to be longer.

In order for the particles to remain aligned vertically (if they didn't there would be a vacuum created in the middle of space, which doesn't happen in this situation), the particles on the longer (top) section of wing must travel FASTER over the surface. The faster a liquid travels over a surface, the lower the pressure on that surface, so viola, lower pressure on the top of the wing creates LIFT.

Okay, so what does that have to do with liquid in a pipe? Well, imagine the same air situation as above, but instead of looking from the side, look at it from the end. Now arrange a series of small wings all around the center circle (tube) of air, arranged like a pinwheel. You can easily see how the air traveling over the surfaces would indeed create lower pressure, but in this situation it would be in 360 degrees, so there wouldn't be any lift.

But...there WOULD be areas of lower pressure all around the outside edges of that tube of air. Now lets jump to water in a pipe with the same model. There is lower pressure on the inside surfaces of the pipe because of the water flowing over (past/through) the inside surfaces of the pipe. The water is held against the pipe by this low pressure, which means the particles of water sort of "stick" to the walls of the pipe. This creates resistance, which slows the movement a bit, which reduces the velocity of liquid over the surface, reducing the effect of the liquid over the surface, etc. See how these all feed each other?

These forces reach a balance. But in complete balance, water won't flow. So we apply an unbalanced force in the form of a circulator pump, which pushes water through the pipe. But remember the sticky inside walls? The water deals with these two forces by creating a layer of water that stays against the pipe, essentially creating a "sheath" of water that lines the inside of the pipe. It is easier for the water in the center of the pipe to slide/flow over its own water lining than the surface of the pipe. This is the friction of the pipe. It still does flow over the inside surface, but not at the same rate as the inner parts of the pipe.

This effect becomes more significant as pipe diameters increase. After all, with larger diameters, the volume of liquid in the middle of the pipe increases faster than the inside surface of the pipe. Looking at a cross-section, Area=3.14 x radius x radius. Circumference = 3.14 x radius x 2.

This accounts for the much greater BTU capacity of larger diameter pipe than smaller pipe, and is also why a small increase in diameter can yield a much larger BTU (think volume) capacity.

Another key factor is the BTU loss of the pipe. Remember the conduction we mentioned between the water and the wall of the pipe? The more surface area, the more loss. The effective BTU "delivery" is affected by the ratio of volume passing through the middle of the pipe without significant loss MINUS the loss from contact with the pipe wall (and the subsequent loss of that pipe wall to ambient air, other surfaces, etc). Additionally, the 'sticky layer' of liquid against the pipe has a bit of an insulative value, further reducing the heat loss in a larger diameter pipe.

This is why larger diameter pipe usually has LESS heat loss than smaller diameter pipe. It is also why larger pipe has LESS friction loss than smaller pipe. Ever try to suck a McDonald's milkshake through a coffee stirrer? It's much easier through a larger straw, even though you are actually moving more material.

An example where all these forces are very well depicted is in Lava tubes. The lava doesn't melt the surrounding rock, yet the lava stays very hot and flows very quickly through these tubes vs flowing in open air. But- you never see very small diameter lava tubes! There is a balance it reaches between the temp/pressure and the tube diameter. It's really something to see!

...see next post...

Disclaimer:
CoalisCoolxWarm

Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

### Re: omg now what am i going to do?

Disclaimer: Some of the descriptions I used are not the exact physical way it works on a molecular level. I've intentionally skipping things like the special bonds of water and such, which may disappoint the chemists and physicists among us, but the description holds true- even where the actual forces may be slightly different than I've outlined

Back to the your question...what diameter of pipe?

Well, that depends

I like the larger diameters. Less loss, less friction, less stress on pumps, more BTU capabilities. I wouldn't waste extra money on AL-PEX, as it would actually increase the heat loss and I don't see a purpose for it in your system.

Your system is designed for a larger main pipe. You may be able to 'get away with' smaller, but typically slower flow in larger volume is better and more efficient.

Note that just the opposite is true at the radiant portion of a system. Thin walled, smaller diameter pipes for baseboard heaters allow more heat to be radiated to heat the room.

I like to use 1.25" or sometimes even 1.5" pipe as the main loop, 1" in the heat loop main trunk, then tee that with 1" to two .75" lines with a balancing valve on each of the .75" lines that run to the opposite ends of a room's baseboard. As close to the middle of the baseboard, I bring each end back to another tee of .75" x .75" to the 1" return line and back to the closely spaced tees to dump back into the main loop.

I understand you are using a liquid to air heat exchanger, right? I haven't used those, but may add one this summer to better tie our forced air system into the hydronic, not sure. I have looked closely at liquid to liquid heat exchangers. I mention it as I am going to tell you what I "think" but without the experience with that particular part, someone with "experience" can easily correct what I may think Experience usually trumps theory

From what I've read, the heat exchangers work just like a radiator. Higher resistance and the need for increased surface area. I'd use larger diameter pipe and more incoming BTUs to get more efficient heat out of the heat exchanger.

I'd use 1.25" as the main loop if possible, or a faster pump with 1" which will have more wear, but likely not significant risk.

Hope this helps!
CoalisCoolxWarm

Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

### Re: omg now what am i going to do?

CoalisCoolxWarm wrote:Disclaimer: Some of the descriptions I used are not the exact physical way it works on a molecular level. I've intentionally skipping things like the special bonds of water and such, which may disappoint the chemists and physicists among us, but the description holds true- even where the actual forces may be slightly different than I've outlined

Back to the your question...what diameter of pipe?

Well, that depends

I like the larger diameters. Less loss, less friction, less stress on pumps, more BTU capabilities. I wouldn't waste extra money on AL-PEX, as it would actually increase the heat loss and I don't see a purpose for it in your system.

Your system is designed for a larger main pipe. You may be able to 'get away with' smaller, but typically slower flow in larger volume is better and more efficient.

Note that just the opposite is true at the radiant portion of a system. Thin walled, smaller diameter pipes for baseboard heaters allow more heat to be radiated to heat the room.

I like to use 1.25" or sometimes even 1.5" pipe as the main loop, 1" in the heat loop main trunk, then tee that with 1" to two .75" lines with a balancing valve on each of the .75" lines that run to the opposite ends of a room's baseboard. As close to the middle of the baseboard, I bring each end back to another tee of .75" x .75" to the 1" return line and back to the closely spaced tees to dump back into the main loop.

I understand you are using a liquid to air heat exchanger, right? I haven't used those, but may add one this summer to better tie our forced air system into the hydronic, not sure. I have looked closely at liquid to liquid heat exchangers. I mention it as I am going to tell you what I "think" but without the experience with that particular part, someone with "experience" can easily correct what I may think Experience usually trumps theory

From what I've read, the heat exchangers work just like a radiator. Higher resistance and the need for increased surface area. I'd use larger diameter pipe and more incoming BTUs to get more efficient heat out of the heat exchanger.

I'd use 1.25" as the main loop if possible, or a faster pump with 1" which will have more wear, but likely not significant risk.

Hope this helps!

no I was using a liquid to liquid exchanger to isolate the two boilers. My original pex was not o2 barrier type.
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil

### Re: omg now what am i going to do?

Thanks for the info. I have it set up temporarily with 1 inch pex al pex and see I should have gone with 1 1/4 o2. I have been noticing that I can feel the heat and it is melting the snow on the ground under it so the aluminum would explain that. I may buy the right pipe and sell what I have on ebay or something.
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil

### Re: omg now what am i going to do?

I am thinking about upgrading to a ka6 do you know the outlet pipe size on these boilers?
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil

### Re: omg now what am i going to do?

I don't know if anybody mentioned it, but O2 barrier is different than AL-PEX, though most of that is also O2 barrier. Clear as mud, eh?

What is the BTU rating of your heat exchanger? The ones I looked at before came in multiple ratings, mostly based on size and number of plates.

Trying to check to make sure you are consuming enough BTUs and aren't getting in a situation where you can't move and use enough, leading to an inevitable boiler overheat. Hope you don't mind all the Q's
CoalisCoolxWarm

Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

### Re: omg now what am i going to do?

My KA6 instructions said 1 1/4,...to start. I belief the fitting on the boiler is 2 inches. I bushed down.
Carbon12

Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice/Anthracite
Other Heating: Heat Pump/Forced Hot Air Oil Furnace

### Re: omg now what am i going to do?

I don't mind the questions I just dont know how to answer some times. I am presently not using the heat exchanger because of the o2 barrier pipe.I figured I didn't need it now. I will have to get back to you on its BTUs I don't know what it is right now. The boler overheated because the air restriction plate on the blower came off. The blower turned off at the set temp but now there was a big opening for a lot of air to feed the fire.
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil

### Re: omg now what am i going to do?

Why do I like your posting so much?
good job - hope to read more!
Kind Regards
Sting

CoalisCoolxWarm wrote:Disclaimer: Some of the descriptions I used are not the exact physical way it works on a molecular level. I've intentionally skipping things like the special bonds of water and such, which may disappoint the chemists and physicists among us, but the description holds true- even where the actual forces may be slightly different than I've outlined

Back to the your question...what diameter of pipe?

Well, that depends

I like the larger diameters. Less loss, less friction, less stress on pumps, more BTU capabilities. I wouldn't waste extra money on AL-PEX, as it would actually increase the heat loss and I don't see a purpose for it in your system.

Your system is designed for a larger main pipe. You may be able to 'get away with' smaller, but typically slower flow in larger volume is better and more efficient.

Note that just the opposite is true at the radiant portion of a system. Thin walled, smaller diameter pipes for baseboard heaters allow more heat to be radiated to heat the room.

I like to use 1.25" or sometimes even 1.5" pipe as the main loop, 1" in the heat loop main trunk, then tee that with 1" to two .75" lines with a balancing valve on each of the .75" lines that run to the opposite ends of a room's baseboard. As close to the middle of the baseboard, I bring each end back to another tee of .75" x .75" to the 1" return line and back to the closely spaced tees to dump back into the main loop.

I understand you are using a liquid to air heat exchanger, right? I haven't used those, but may add one this summer to better tie our forced air system into the hydronic, not sure. I have looked closely at liquid to liquid heat exchangers. I mention it as I am going to tell you what I "think" but without the experience with that particular part, someone with "experience" can easily correct what I may think Experience usually trumps theory

From what I've read, the heat exchangers work just like a radiator. Higher resistance and the need for increased surface area. I'd use larger diameter pipe and more incoming BTUs to get more efficient heat out of the heat exchanger.

I'd use 1.25" as the main loop if possible, or a faster pump with 1" which will have more wear, but likely not significant risk.

Hope this helps!
Sting

Other Heating: BurnHAM=NG-gas

### Re: omg now what am i going to do?

GaryFerg wrote:I don't mind the questions I just dont know how to answer some times. I am presently not using the heat exchanger because of the o2 barrier pipe.I figured I didn't need it now. I will have to get back to you on its BTUs I don't know what it is right now. The boler overheated because the air restriction plate on the blower came off. The blower turned off at the set temp but now there was a big opening for a lot of air to feed the fire.

Often with outdoor units, people use antifreeze treated loop, then heat exchanger to heat the inside water-only loop. What is your plan to prevent freezing if your furnace goes down?

@Sting- Thanks! I try to explain things that answer the questions I had. It's wordy because I was a very curious fellow!
CoalisCoolxWarm

Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

### Re: omg now what am i going to do?

Ha Plan? whats that? I was using anti freeze I lost a lot of it when a circulator went bad. it is just too expensive to fill 50 gallons. As long as its moving I guess it will be alright. I can keep the boiler warm with a kerosene heater and the underground pipe seems to be okay. With all that super cold weather we had the frost was only at 3 inches. I just think its more efficient without the heat exchanger but I can always add it back in if need be. I am trying to make it the most efficient I can. ( use less Coal) . I am not sure if the way I have it tied to the other boiler is the best way but it works. If I do switch to the keystoker I can really eliminate the oil burner altogether. I presently use it to make domestic hot water and I back up for the hand feed.
I feed the oil boiler at a pipe from the bottom and from the top of the coal boiler. The return is from the top of the oil boiler to the bottom of the coal boiler all via pex. The circulator is on the return side of the coal boiler. its a grundfos 20 gpm I think. Another benefit to not using the heat exchanger is that I have cooler return temperature to the coal boiler which is easier on that circulator. I am wondering now if I should redo everything with inch and a quarter pex. That means changing everything like valves and fittings which can add up.
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil

### Re: omg now what am i going to do?

There are a lot of different ways to do things. Many people have their opinions and preferences. Different methods have different pros and cons. This is my preference, perhaps others will share theirs.

IF you are planning a replumb, I prefer to use 1.25" black iron and/or copper in the main loop and between boilers. I also use a zone pump for each zone with automatic check valve with closely spaced tees and a heat trap loop on the return side. I have a single circulator on the boiler- return side is preferred as the boiler is a big source of resistance.

Some people use zone switches. I have seen and like the looks of the pre-fabbed PEX manifolds, but haven't used them myself. I've helped troubleshoot them, but not as a designer or installer.

With only two boilers, you can run them in series like you are. For an interesting read, google 'parallel boiler installation' It is an option, but mostly for multiple and redundant boilers like in a large apartment building and such. In a residential setting, two series systems can be okay, but I wouldn't add any more than 2 without using parallel systems.

I am going to be adding a stoker into my system this Spring/Summer. I have the oil boiler system offline during a remodel of the house where I am replumbing most of the baseboard, as we are adding 2.5"-3" of wall thickness in most rooms and have to move the baseboard accordingly.

I plan to run them in series, similar to what you describe. Advantages include circulation through the oil boiler (which will be idle most of the time), preventing stagnation and crud buildup, and larger primary (main) loop water volume- two jackets plus piping.

I am *considering* adding a section of parallel piping at the oil boiler return with diverter valves to allow me to bypass the oil boiler pump when using the stoker, yet I can switch over to the oil boiler's pump in the event of a failure. I am not sure yet and plan to solicit opinions on this- one pump or two in the main loop....

I've mentioned that I have concerns about using PEX too close to the boiler and as part of the main loop. I still hold that opinion.

In case you didn't know, they also make flanges with integrated valves for the pumps. Really nice if you have to replace a pump- no draining the system or adding air Cartridge pumps are good for that, too, especially on the zones, but I still use the flanges with valves, allowing me to isolate any zone at any time for any reason. That's real handy while remodeling! (I've been tempted to bring the system online with just a few zones, but keep telling myself to be patient until Spring!)

You will need to use controllers to allow your boilers to work together (primary and fail-over/secondary) and still control your zones. I can't give you part numbers for that, as I haven't selected one yet- another point of questions when the time comes

Oh- be sure NOT to use pumps with check valves in your main loop! Otherwise, when the pump from one boiler is running, it won't be able to pump through the other one It is possible to wire them so they both run with either boiler, but that seems...wasteful to me.

I archived the references and designs I used when my computer crashed a while back. Let me see if I can dig one up that may help...
CoalisCoolxWarm

Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

### Re: omg now what am i going to do?

There are a few things I dont under stand like heat trap loop on the return side. what is that? Also I do have the check valve in my main loop so when the outside boiler is trying to catch up and is below the circulator set point the one in the house isn't trying to heat two boilers. Any info you can give me is much appreciated. I am a learn as you go type.
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil

### Re: omg now what am i going to do?

GaryFerg wrote:There are a few things I dont under stand like heat trap loop on the return side. what is that? Also I do have the check valve in my main loop so when the outside boiler is trying to catch up and is below the circulator set point the one in the house isn't trying to heat two boilers. Any info you can give me is much appreciated. I am a learn as you go type.

A heat trap is when your returning line (from a zone loop) is plumbed to dip below the primary loop about 12", then comes up and attaches with a tee facing downward to the primary loop. This prevents a passive reverse-circulation or simply heat loss back up the cooler return line from the primary when the zone is not in service.

Heat rises, so the supply of the zone is up, the return is down. Technically, when using the integrated check valves in the zone pump, it shouldn't be much of an issue, but it doesn't take much to reach 'best' over 'good enough' Personal preference.

It sounds like the check valve is in your outside boiler circuit, using the heat exchanger. That's okay. But when you install the stoker inside and in series with your oil boiler, no check valve

One thing to keep in mind. I haven't installed any outdoor boilers. I saw an outdoor WOOD boiler that referred to being a non-pressurized system, so check your manual to make sure your coal boiler isn't like that. If it is...consider the info I'm giving you on much of this to be for the closed systems (all pressurized).

I am also not an expert, nor pretend to be. I am sharing what I have learned and experienced It doesn't seem that anyone is stepping in and correcting what I share, so must be okay

I read very little about the non-pressurized systems, but don't have any experience with them.

CoalisCoolxWarm

Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

### Re: omg now what am i going to do?

This is a pressurized system. Its a add on boiler I put out in my now insulated shed which doubles for a winter place for the plants. I am not using the heat exchanger at this time. The check valve flow valve is in the circulator in the shed. My inside setup has flow valves so a bypass maybe isn't necessary. It was very cold last night again 4 degrees or less over night. I had to turn on the oil burner because the coal couldn't get up to temperature. I think there is air in the system but my air release valve is stuck open so it is capped. I have to replace it I guess. Its not too well sealed around the windows that my temporary pipe runs through so I have to get some plastic and try to seal it up better. It was working great until last night. Oh the keystoker will go out in the shed again not in the basement. I don't know how I would get it down there anyway. by the way I don't see a btu rating on the heat exchanger, it is a bl26-60 I guess that means 60 plates. I havent counted them but that looks about right. Anyway I probably will not use it again to save on heat loss.
Last edited by GaryFerg on Thu Feb 27, 2014 11:54 am, edited 1 time in total.
GaryFerg

Hand Fed Coal Boiler: Energy King boiler
Hand Fed Coal Stove: Harmon TLC 2000
Coal Size/Type: Nut
Other Heating: oil