1 1/4 vs. 1 tubing, Chimmney question

[greg in MN]

Will 1 1/4 tubing, 1 1/8 inside handle much more water then 1 inch inside tubing? Slant fin est. 127,000. Using antifreeze with a 100 foot run.

I have a cement chimmney in detached garage with no liner. Do I need a liner? Guess would have to be metal as would be hard to install clay liner.

Looking at Econoburn 150.

Thank you

 

[in hot water]

pex, flowing water at 170F, 20 F delta T

Here is the spec for 1" and 1-1/4"

11.1 gpm for 1-1/4" vs 7.4 gpm on the 1"

Also the amount of BTU/hr. each will carry. This is a safe continuous operation at 4 fps.

 

[Gooserider]

Will 1 1/4 tubing, 1 1/8 inside handle much more water then 1 inch inside tubing? Slant fin est. 127,000. Using antifreeze with a 100 foot run.

I have a cement chimmney in detached garage with no liner. Do I need a liner? Guess would have to be metal as would be hard to install clay liner.

Looking at Econoburn 150.

Thank you

I think IHW answered your pipe question fairly well, 1.25" is MUCH better - however note that his specs were using water, and even then the 1.25" wasn't moving quite enough BTU's at the specs he gave. If I remember the stuff I've read, glycol mix is harder to pump, and carries less heat per gallon, so I would suspect that 1.25 would still be a bit shy... OTOH, if you did double runs of either 1" or 1.25" then you would probably be in really great shape.

In terms of the liner, it depends on the chimney -

1. Is it in GOOD condition? - if not a liner can be part of bringing it up to code, especially if insulated.

2. How big is the cross section? Is it an inside or outside chimney? If it's got to much of a cross section, your draft will suffer... Unless the manufacturer manual says otherwise, optimal is to have the same size cross section area as the boiler outlet (usually 6 or 8" diameter, or about 28 sq" for a 6" flue, or 50sq" for an 8") Code says maximum is 2x cross section on an inside chimney, or 3x on an outside one - A liner is the best way to bring an oversized flue into specs.

3. Is the flue clay tile lined? Code usually requires this for wood burners, if it isn't you will probably need a liner...

Best bet may be to have a chimney sweep or your local fire department safety guy take a look and tell you if you are in doubt.

Gooserider

 

[heaterman]

Will 1 1/4 tubing, 1 1/8 inside handle much more water then 1 inch inside tubing? Slant fin est. 127,000. Using antifreeze with a 100 foot run.

I have a cement chimmney in detached garage with no liner. Do I need a liner? Guess would have to be metal as would be hard to install clay liner.

Looking at Econoburn 150.

Thank you

Is that 100' total or is the loop length actually 200'?

 

[greg in MN]

It is 102 feet between the buildings.

Greg

 

[heaterman]

It is 102 feet between the buildings.

Greg

So what you need to calculate is the flow and head through approx 200' of tube to make the loop out and back right?

 

[greg in MN]

So what you need to calculate is the flow and head through approx 200’ of tube to make the loop out and back right?


Yes, will the 1 1/8 inside diameter have enough water with a small pump to heat house.

 

[heaterman]

So what you need to calculate is the flow and head through approx 200’ of tube to make the loop out and back right?


Yes, will the 1 1/8 inside diameter have enough water with a small pump to heat house.

Here's what I crunched out as far as flow with different circs and pex diameters. These are for standard pex sizes, 1" and 1-1/4". Forget about the I.D. 1-1/8" stuff. Simplify your life and just go with industry standard nomenclature.

These are using 200' round trip with a normal number of fittings and valves thrown in to make it real.

using 1" pex with a 15-58 you get 6.7 GP..... not enough unless you can generate a 40* temp drop supply to return.

using 1" pex with a 26-99 you get smidge over 10 GPM and double the head. would carry you load with about a 30* temp drop

using 1-1/4" pex and a 15-58 you get about 9.5 GPM, again enough flow if you can get a 30* drop

using 1-1/4" pex and a 26-64 or a 26-99 on speed 2 you get 12.8 GPM which nails your load with a 20* temp drop.

The keys here are how much temp drop your heating system will generate and how much circ you want to pay the electric bill for.

Typically if you had a well designed radiant slab heating system, a 40* drop would not be out of the question. I have done a few panel rad systems that will hit that also. If you are using baseboard or a forced air type heat exchanger you are going to be hard pressed to see more than 20*.

Choose your poison.

 

[greg in MN]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

 

[heaterman]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

Hmmmmmm...............rubbing chin whiskers.............You might be able to run your loads in series with the right controls in place and wind up with a 30-40* drop. The theory would be to run through the F/A HX first dropping probably 10-12* in temp and then continue on to the floor zones which should easily add another 20* if the flow rate is correct. You'd probably want to serve both of those loads via a primary loop arrangement.

 

[pybyr]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

Hmmmmmm...............rubbing chin whiskers.............You might be able to run your loads in series with the right controls in place and wind up with a 30-40* drop. The theory would be to run through the F/A HX first dropping probably 10-12* in temp and then continue on to the floor zones which should easily add another 20* if the flow rate is correct. You'd probably want to serve both of those loads via a primary loop arrangement.

I don't want to hijack the thread- but the above suggestion raises an interesting point that I've wanted to ask anyway- radiant floor is comfortable and efficient, but sometimes inherently slow to respond; warm air is fast to respond, but not so comfortable or efficient. Especially for someone (like me) who'd have to install any retrofit radiant under 2-3 inches of wood floor (old house-thick floors)- which might limit the radiant's ability to meet total peak BTU load, might one get some benefit from using radiant as "baseload" heat for many conditions, augmented by warm air when there's a need for a fast warm up or more BTUs than one can wisely send through an existing thick wood floor?

 

[heaterman]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

Hmmmmmm...............rubbing chin whiskers.............You might be able to run your loads in series with the right controls in place and wind up with a 30-40* drop. The theory would be to run through the F/A HX first dropping probably 10-12* in temp and then continue on to the floor zones which should easily add another 20* if the flow rate is correct. You'd probably want to serve both of those loads via a primary loop arrangement.

I don't want to hijack the thread- but the above suggestion raises an interesting point that I've wanted to ask anyway- radiant floor is comfortable and efficient, but sometimes inherently slow to respond; warm air is fast to respond, but not so comfortable or efficient. Especially for someone (like me) who'd have to install any retrofit radiant under 2-3 inches of wood floor (old house-thick floors)- which might limit the radiant's ability to meet total peak BTU load, might one get some benefit from using radiant as "baseload" heat for many conditions, augmented by warm air when there's a need for a fast warm up or more BTUs than one can wisely send through an existing thick wood floor?

Hijack to your hearts content! It's a good question and one that I run into quite often.

What you are talking about is usually easily set up with a two stage thermostat. The in/sub floor is used as the first "stage" and the F/A is the second stage which is called on when the first stage can't reach the setpoint. There are a few different control strategies as far as lag times between stages and what exactly you are powering up but using the floor as the baseload works very well. For something with a lot of options, look at Tekmar controls.

 

[heaterman]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

Hmmmmmm...............rubbing chin whiskers.............You might be able to run your loads in series with the right controls in place and wind up with a 30-40* drop. The theory would be to run through the F/A HX first dropping probably 10-12* in temp and then continue on to the floor zones which should easily add another 20* if the flow rate is correct. You'd probably want to serve both of those loads via a primary loop arrangement.

ADDENDUM TO ABOVE; the thing to remember is that you only need that maximum flow/btu delivery at design conditions when everything is calling for heat. Most of the time that 6-7GPM would be sufficient at a 20* temp drop. If your heat emitters can swing the 40* temp drop you could probably get by with that 1"/15-58 setup. It would be max'd out though and if you added anything else such as DHW it wouldn't carry it.

 

[Gooserider]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

Hmmmmmm...............rubbing chin whiskers.............You might be able to run your loads in series with the right controls in place and wind up with a 30-40* drop. The theory would be to run through the F/A HX first dropping probably 10-12* in temp and then continue on to the floor zones which should easily add another 20* if the flow rate is correct. You'd probably want to serve both of those loads via a primary loop arrangement.

ADDENDUM TO ABOVE; the thing to remember is that you only need that maximum flow/btu delivery at design conditions when everything is calling for heat. Most of the time that 6-7GPM would be sufficient at a 20* temp drop. If your heat emitters can swing the 40* temp drop you could probably get by with that 1"/15-58 setup. It would be max'd out though and if you added anything else such as DHW it wouldn't carry it.

The other thing if I am understanding Siegenthaler and friends correctly is that going with the larger tubes, or dual 1" linesets might cost more up front for materials, but in addition to having more capacity if needed, would have lower operating costs by allowing a lower flow velocity, which decreases the head loss, and energy needed to move a given number of BTU's so that you can use a smaller circ that will draw less energy over the life of the system... Correct me if I'm wrong HM, but from what I've been seeing, it looked like while you want to keep the flow velocity between 2 and 4 feet per minute, your electric bill will be a lot happier if you target a 2 fpm flow rather than a 4fpm flow.

I know there is a definite tradeoff between pipe size and operating costs, and that going above the 4fpm flow has major cost impacts... However, I haven't quite got my head wrapped around the amount of benefit you get from upsizing the pipe in the 2-4fpm range, and how to tell if it's worth it...

Gooserider

 

[heaterman]

The chimney is inside building, going to put in metal insert.

I have a heat exchanger in forced air furnace and 8 zone radiant of 2400 feet total in cement floor.

Thank you for all the help.

Greg

Hmmmmmm...............rubbing chin whiskers.............You might be able to run your loads in series with the right controls in place and wind up with a 30-40* drop. The theory would be to run through the F/A HX first dropping probably 10-12* in temp and then continue on to the floor zones which should easily add another 20* if the flow rate is correct. You'd probably want to serve both of those loads via a primary loop arrangement.

ADDENDUM TO ABOVE; the thing to remember is that you only need that maximum flow/btu delivery at design conditions when everything is calling for heat. Most of the time that 6-7GPM would be sufficient at a 20* temp drop. If your heat emitters can swing the 40* temp drop you could probably get by with that 1"/15-58 setup. It would be max'd out though and if you added anything else such as DHW it wouldn't carry it.

The other thing if I am understanding Siegenthaler and friends correctly is that going with the larger tubes, or dual 1" linesets might cost more up front for materials, but in addition to having more capacity if needed, would have lower operating costs by allowing a lower flow velocity, which decreases the head loss, and energy needed to move a given number of BTU's so that you can use a smaller circ that will draw less energy over the life of the system... Correct me if I'm wrong HM, but from what I've been seeing, it looked like while you want to keep the flow velocity between 2 and 4 feet per minute, your electric bill will be a lot happier if you target a 2 fpm flow rather than a 4fpm flow.

I know there is a definite tradeoff between pipe size and operating costs, and that going above the 4fpm flow has major cost impacts... However, I haven't quite got my head wrapped around the amount of benefit you get from upsizing the pipe in the 2-4fpm range, and how to tell if it's worth it...

Gooserider

That 4 feet/second is a long established industry practice for a number of reasons besides circ sizing, electrical load and head developed. One thing often over looked is that velocities above that benchmark can and do cause erosion in fittings and pipe. Most of the pex fittings I see people purchase are the garden variety soft brass type which are fine for most uses. Once you get above 5-6fps however, all bets are off in my book. I have been called out to installations only 4-5 years old for leak problems and found those fittings worn down internally to the point where they are pitted and you can about crush them with your fingers. When I run into that I can be about 100% certain that I'll find the installer has a high head circ like an 0011 or 26-99 tied on the other end of the tube and the flow rate will be 6+. A bronze fitting like Viega makes is more durable in the long run and more resistant to weird water problems. You can also encounter the same problem in copper tube and fittings used elsewhere in the system. I see at least one furnace type coil per year that has developed pits in it for the same reason. High head can also cause problems with erosion in shut off valves of different types as well as some zone valves. Going a size up on main piping is always a good idea in my book if for nothing less than the fact that situations change and five years down the road you might want to add something else to the system that was not considered before. Realistically, I'd rather see a person save money on his control system or something like that rather than just squeak by on the main tubing size. It's a lot easier to change controls and or circs later on than it is changing your underground lines.

 

[pybyr]

I know there is a definite tradeoff between pipe size and operating costs, and that going above the 4fpm flow has major cost impacts... However, I haven't quite got my head wrapped around the amount of benefit you get from upsizing the pipe in the 2-4fpm range, and how to tell if it's worth it...Gooserider

I think I recall from some Siggy article or other seemingly knowledgeable source that 4fps is a normal upper limit in residential use because anything above that can be noisy. Apparently there a number higher than 4 fps- I do not recall how much higher- where one is flirting with eventual internal erosion of the pipe to the point of eventual leaks.

[edit- my post became moot right after I posted it, as Heaterman, moments before, said sort of the same thing but with more detail/ observations from experience)

 

[heaterman]

I know there is a definite tradeoff between pipe size and operating costs, and that going above the 4fpm flow has major cost impacts... However, I haven't quite got my head wrapped around the amount of benefit you get from upsizing the pipe in the 2-4fpm range, and how to tell if it's worth it...Gooserider

I think I recall from some Siggy article or other seemingly knowledgeable source that 4fps is a normal upper limit in residential use because anything above that can be noisy. Apparently there a number higher than 4 fps- I do not recall how much higher- where one is flirting with eventual internal erosion of the pipe to the point of eventual leaks.

[edit- my post became moot right after I posted it, as Heaterman, moments before, said sort of the same thing but with more detail/ observations from experience)

Yep. Flow noise can be aggravating as a dripping faucet or the wrong kind of mother in law.

(Mine is a peach)

 

[pybyr]

[
I don't want to hijack the thread- but the above suggestion raises an interesting point that I've wanted to ask anyway- radiant floor is comfortable and efficient, but sometimes inherently slow to respond; warm air is fast to respond, but not so comfortable or efficient. Especially for someone (like me) who'd have to install any retrofit radiant under 2-3 inches of wood floor (old house-thick floors)- which might limit the radiant's ability to meet total peak BTU load, might one get some benefit from using radiant as "baseload" heat for many conditions, augmented by warm air when there's a need for a fast warm up or more BTUs than one can wisely send through an existing thick wood floor?

Hijack to your hearts content! It's a good question and one that I run into quite often.

What you are talking about is usually easily set up with a two stage thermostat. The in/sub floor is used as the first "stage" and the F/A is the second stage which is called on when the first stage can't reach the setpoint. There are a few different control strategies as far as lag times between stages and what exactly you are powering up but using the floor as the baseload works very well. For something with a lot of options, look at Tekmar controls.[/quote]

Thanks, heaterman

 

[Gooserider]

I totally understand the idea that 4fpm should be the upper limit of what one should allow in a system, and the reasons for it... I've also seen various articles that say you should have a MINIMUM flow rate of 2fpm in order to entrain any air bubbles in the system and carry them to where they can be removed.

However, what I've noticed is a tendency for most folks quoting numbers is to "target" 4fpm as the desired rate, as opposed to the 2 or 3fpm number which would give presumably lower operating costs... I know that Siggy and friends have lots of lengthy formulas (and expensive proprietary software to solve them) for figuring out flow rates, operating costs, and so forth... Is there a reason why this software (or it's users?) tends to target 4fpm as opposed to the lower numbers?

Perhaps equally useful, are there any good "quick and dirty" rules of thumb if one has solved for a 4fpm rate to see what increasing a pipe size or two would do both for flow rates and operating costs?

Some of this is me trying to figure out what I'll need for my own setup, and some of it is wanting to be able to offer more useful advice to others, without having the fancy software that probably won't run on my Linux system any way... For instance in the case of the OP's question, (to drag it back to the original subject :coolsmirk: ) I had suggested using double runs of 1" tube, as opposed to 1.25" or larger. My reasoning was that I know from lots of comments that >1" size PEX tubing seems to be much harder to find and more expensive than <=1", and having a gut feeling that 1.25" might be a bit marginal... Punching numbers on the nominal sizes, says that 2 1" ID tubes would have a cross section of 1.5^2" as opposed to 1.23^2" for a 1.25" tube... So how "right" was I? How much benefit would there be from that extra 1/4^2"?

Gooserider

 

[heaterman]

I totally understand the idea that 4fpm should be the upper limit of what one should allow in a system, and the reasons for it... I've also seen various articles that say you should have a MINIMUM flow rate of 2fpm in order to entrain any air bubbles in the system and carry them to where they can be removed.

However, what I've noticed is a tendency for most folks quoting numbers is to "target" 4fpm as the desired rate, as opposed to the 2 or 3fpm number which would give presumably lower operating costs... I know that Siggy and friends have lots of lengthy formulas (and expensive proprietary software to solve them) for figuring out flow rates, operating costs, and so forth... Is there a reason why this software (or it's users?) tends to target 4fpm as opposed to the lower numbers?

Perhaps equally useful, are there any good "quick and dirty" rules of thumb if one has solved for a 4fpm rate to see what increasing a pipe size or two would do both for flow rates and operating costs?

Some of this is me trying to figure out what I'll need for my own setup, and some of it is wanting to be able to offer more useful advice to others, without having the fancy software that probably won't run on my Linux system any way... For instance in the case of the OP's question, (to drag it back to the original subject :coolsmirk: ) I had suggested using double runs of 1" tube, as opposed to 1.25" or larger. My reasoning was that I know from lots of comments that >1" size PEX tubing seems to be much harder to find and more expensive than <=1", and having a gut feeling that 1.25" might be a bit marginal... Punching numbers on the nominal sizes, says that 2 1" ID tubes would have a cross section of 1.5^2" as opposed to 1.23^2" for a 1.25" tube... So how "right" was I? How much benefit would there be from that extra 1/4^2"?

Gooserider

4fps vs 2fps = law of diminishing returns. In other words increasing the pipe/tube size to obtain the lower number really doesn't yield any great benefits vompared to the 4fps flow rate.

Rules of thumb:

1/2" = 1.5 GPM
3/4" = 4 GPM
1" = 8 GPM
1-1/4" = 15GPM
1=1/2 " = 22GPM


In all but very long runs ( over 250' equivalent length) a pair of 1: lines will just about equal a single 1-1/4". When you start comparing 2 smaller lines vs a single larger bore tube velocity comes into play in the form of laminar vs turbulent flow dynamics. I'm not going to get into the physics of that.

 

[Gooserider]

I totally understand the idea that 4fpm should be the upper limit of what one should allow in a system, and the reasons for it... I've also seen various articles that say you should have a MINIMUM flow rate of 2fpm in order to entrain any air bubbles in the system and carry them to where they can be removed.

However, what I've noticed is a tendency for most folks quoting numbers is to "target" 4fpm as the desired rate, as opposed to the 2 or 3fpm number which would give presumably lower operating costs... I know that Siggy and friends have lots of lengthy formulas (and expensive proprietary software to solve them) for figuring out flow rates, operating costs, and so forth... Is there a reason why this software (or it's users?) tends to target 4fpm as opposed to the lower numbers?

Perhaps equally useful, are there any good "quick and dirty" rules of thumb if one has solved for a 4fpm rate to see what increasing a pipe size or two would do both for flow rates and operating costs?

Some of this is me trying to figure out what I'll need for my own setup, and some of it is wanting to be able to offer more useful advice to others, without having the fancy software that probably won't run on my Linux system any way... For instance in the case of the OP's question, (to drag it back to the original subject :coolsmirk: ) I had suggested using double runs of 1" tube, as opposed to 1.25" or larger. My reasoning was that I know from lots of comments that >1" size PEX tubing seems to be much harder to find and more expensive than <=1", and having a gut feeling that 1.25" might be a bit marginal... Punching numbers on the nominal sizes, says that 2 1" ID tubes would have a cross section of 1.5^2" as opposed to 1.23^2" for a 1.25" tube... So how "right" was I? How much benefit would there be from that extra 1/4^2"?

Gooserider

4fps vs 2fps = law of diminishing returns. In other words increasing the pipe/tube size to obtain the lower number really doesn't yield any great benefits vompared to the 4fps flow rate.

Rules of thumb:

1/2" = 1.5 GPM
3/4" = 4 GPM
1" = 8 GPM
1-1/4" = 15GPM
1=1/2 " = 22GPM


In all but very long runs ( over 250' equivalent length) a pair of 1: lines will just about equal a single 1-1/4". When you start comparing 2 smaller lines vs a single larger bore tube velocity comes into play in the form of laminar vs turbulent flow dynamics. I'm not going to get into the physics of that.

OK, thanks, it is very helpful to have that info... so the dual 1" lines don't offer a significant performance benefit, and there isn't a good operation cost benefit from going below 4fps flow rates...

However I'm still thinking there might be noticeable cost benefits over 1.25" - So I did some price shopping... Looking at FleaBay just for price comparison, I saw lots of listings for 1" tubing, with probably the most common relevant one being 300' of 1" O2 barrier (no brand specified) for $219 w/ shipping - or about $0.70 / foot... NO listings for 1.25" - so I went to another vendor site, (one that has been mentioned by some on here as a good low cost source) and found that 1.25" was 2-3 times the cost of 1" depending on coil length, with almost as big jumps for 1.5" and 2". All the prices were higher, but still for 300 foot coils of Aquapex brand - 1"=$375, (or 100' for $105 each) 1.25" =$750, 1.5"=$865 and 2"=$1044... I didn't price the end fittings, but it seems to me from those prices that it would be as cheap or cheaper to do multiple runs of 1" as it would be to do the over 1" sizes... (and your rough rule above suggests that 3x1" is going to give about the same performance as 1.5")

Gooserider

 

[heaterman]

I totally understand the idea that 4fpm should be the upper limit of what one should allow in a system, and the reasons for it... I've also seen various articles that say you should have a MINIMUM flow rate of 2fpm in order to entrain any air bubbles in the system and carry them to where they can be removed.

However, what I've noticed is a tendency for most folks quoting numbers is to "target" 4fpm as the desired rate, as opposed to the 2 or 3fpm number which would give presumably lower operating costs... I know that Siggy and friends have lots of lengthy formulas (and expensive proprietary software to solve them) for figuring out flow rates, operating costs, and so forth... Is there a reason why this software (or it's users?) tends to target 4fpm as opposed to the lower numbers?

Perhaps equally useful, are there any good "quick and dirty" rules of thumb if one has solved for a 4fpm rate to see what increasing a pipe size or two would do both for flow rates and operating costs?

Some of this is me trying to figure out what I'll need for my own setup, and some of it is wanting to be able to offer more useful advice to others, without having the fancy software that probably won't run on my Linux system any way... For instance in the case of the OP's question, (to drag it back to the original subject :coolsmirk: ) I had suggested using double runs of 1" tube, as opposed to 1.25" or larger. My reasoning was that I know from lots of comments that >1" size PEX tubing seems to be much harder to find and more expensive than <=1", and having a gut feeling that 1.25" might be a bit marginal... Punching numbers on the nominal sizes, says that 2 1" ID tubes would have a cross section of 1.5^2" as opposed to 1.23^2" for a 1.25" tube... So how "right" was I? How much benefit would there be from that extra 1/4^2"?

Gooserider

4fps vs 2fps = law of diminishing returns. In other words increasing the pipe/tube size to obtain the lower number really doesn't yield any great benefits vompared to the 4fps flow rate.

Rules of thumb:

1/2" = 1.5 GPM
3/4" = 4 GPM
1" = 8 GPM
1-1/4" = 15GPM
1=1/2 " = 22GPM


In all but very long runs ( over 250' equivalent length) a pair of 1: lines will just about equal a single 1-1/4". When you start comparing 2 smaller lines vs a single larger bore tube velocity comes into play in the form of laminar vs turbulent flow dynamics. I'm not going to get into the physics of that.

OK, thanks, it is very helpful to have that info... so the dual 1" lines don't offer a significant performance benefit, and there isn't a good operation cost benefit from going below 4fps flow rates...

However I'm still thinking there might be noticeable cost benefits over 1.25" - So I did some price shopping... Looking at FleaBay just for price comparison, I saw lots of listings for 1" tubing, with probably the most common relevant one being 300' of 1" O2 barrier (no brand specified) for $219 w/ shipping - or about $0.70 / foot... NO listings for 1.25" - so I went to another vendor site, (one that has been mentioned by some on here as a good low cost source) and found that 1.25" was 2-3 times the cost of 1" depending on coil length, with almost as big jumps for 1.5" and 2". All the prices were higher, but still for 300 foot coils of Aquapex brand - 1"=$375, (or 100' for $105 each) 1.25" =$750, 1.5"=$865 and 2"=$1044... I didn't price the end fittings, but it seems to me from those prices that it would be as cheap or cheaper to do multiple runs of 1" as it would be to do the over 1" sizes... (and your rough rule above suggests that 3x1" is going to give about the same performance as 1.5")

Gooserider

Hmmmmmm.......looking at a couple hummingbirds fighting over the flowers outside my office window and thinking that the flowers will be covered in snow only 90 days from now...............

But I digress....the flow rates listed above are for copper tube. steel piping will be about 10% more and pex will be about 10% less. Personally I avoid anything over 6GPM in 1" pex due to head issues and having to go with high head circs. 12GPM is about max for 1-1/4" and 19 in 1-1/2". Beyond that you get into 26-99, 0011 or 1400 series Taco circs which are 3x the cost to buy and operate. A 15-58 will move enormous amounts of btu's through a properly designed, low head system.

As for me I would much rather handle and pipe up a single line than two or three. Sometimes space simply doesn't permit anything more than that. I sell Viega O2 barrier pex in my shop/store for $218/100 and it baffles me why wholesalers and supply houses don't stock it. 1-1/2" tube is only $2.62 in 100' rolls.

 

[Gooserider]

<snip>
Hmmmmmm.......looking at a couple hummingbirds fighting over the flowers outside my office window and thinking that the flowers will be covered in snow only 90 days from now...............

But I digress....the flow rates listed above are for copper tube. steel piping will be about 10% more and pex will be about 10% less. Personally I avoid anything over 6GPM in 1" pex due to head issues and having to go with high head circs. 12GPM is about max for 1-1/4" and 19 in 1-1/2". Beyond that you get into 26-99, 0011 or 1400 series Taco circs which are 3x the cost to buy and operate. A 15-58 will move enormous amounts of btu's through a properly designed, low head system.

As for me I would much rather handle and pipe up a single line than two or three. Sometimes space simply doesn't permit anything more than that. I sell Viega O2 barrier pex in my shop/store for $218/100 and it baffles me why wholesalers and supply houses don't stock it. 1-1/2" tube is only $2.62 in 100' rolls.

Well, it sounds like you are doing good pricing in your shop, I was just looking at the Flea-bay prices cause they were handy... I don't try to understand the logic of some of these supply houses, though I will gripe at them on occasion - I figure that if their job is to sell me what I want, my job is to tell them what I want to buy....

I agree it might be more convenient to hook up one pipe set than many, and that might well get reflected in labor bills, but if one is on a budget and doing the DIY thing... It is why I stuck with just saying there would be a cost savings with the multiple lines, but there may be other factors pushing the single set solution as well - everybody has different priorities...

I did keep looking at prices a bit since I'd gotten started, and again looking at FleaBay vendors, it was interesting to note that I didn't see the huge jumps in prices in the smaller tube sizes - 3/8" was $90 / 300' or $250 / 1K, 1/2" was $99 and $275, and 5/8 was the same, 3/4" was $141 and $440... So upsizing on the smaller sizes didn't seem to have a noticeable cost penalty attached to it the way the large sizes did.

Gooserider

 

[rkusek]

I totally understand the idea that 4fpm should be the upper limit of what one should allow in a system, and the reasons for it... I've also seen various articles that say you should have a MINIMUM flow rate of 2fpm in order to entrain any air bubbles in the system and carry them to where they can be removed.

However, what I've noticed is a tendency for most folks quoting numbers is to "target" 4fpm as the desired rate, as opposed to the 2 or 3fpm number which would give presumably lower operating costs... I know that Siggy and friends have lots of lengthy formulas (and expensive proprietary software to solve them) for figuring out flow rates, operating costs, and so forth... Is there a reason why this software (or it's users?) tends to target 4fpm as opposed to the lower numbers?

Perhaps equally useful, are there any good "quick and dirty" rules of thumb if one has solved for a 4fpm rate to see what increasing a pipe size or two would do both for flow rates and operating costs?

Some of this is me trying to figure out what I'll need for my own setup, and some of it is wanting to be able to offer more useful advice to others, without having the fancy software that probably won't run on my Linux system any way... For instance in the case of the OP's question, (to drag it back to the original subject :coolsmirk: ) I had suggested using double runs of 1" tube, as opposed to 1.25" or larger. My reasoning was that I know from lots of comments that >1" size PEX tubing seems to be much harder to find and more expensive than <=1", and having a gut feeling that 1.25" might be a bit marginal... Punching numbers on the nominal sizes, says that 2 1" ID tubes would have a cross section of 1.5^2" as opposed to 1.23^2" for a 1.25" tube... So how "right" was I? How much benefit would there be from that extra 1/4^2"?

Gooserider

4fps vs 2fps = law of diminishing returns. In other words increasing the pipe/tube size to obtain the lower number really doesn't yield any great benefits vompared to the 4fps flow rate.

Rules of thumb:

1/2" = 1.5 GPM
3/4" = 4 GPM
1" = 8 GPM
1-1/4" = 15GPM
1=1/2 " = 22GPM


In all but very long runs ( over 250' equivalent length) a pair of 1: lines will just about equal a single 1-1/4". When you start comparing 2 smaller lines vs a single larger bore tube velocity comes into play in the form of laminar vs turbulent flow dynamics. I'm not going to get into the physics of that.

OK, thanks, it is very helpful to have that info... so the dual 1" lines don't offer a significant performance benefit, and there isn't a good operation cost benefit from going below 4fps flow rates...

However I'm still thinking there might be noticeable cost benefits over 1.25" - So I did some price shopping... Looking at FleaBay just for price comparison, I saw lots of listings for 1" tubing, with probably the most common relevant one being 300' of 1" O2 barrier (no brand specified) for $219 w/ shipping - or about $0.70 / foot... NO listings for 1.25" - so I went to another vendor site, (one that has been mentioned by some on here as a good low cost source) and found that 1.25" was 2-3 times the cost of 1" depending on coil length, with almost as big jumps for 1.5" and 2". All the prices were higher, but still for 300 foot coils of Aquapex brand - 1"=$375, (or 100' for $105 each) 1.25" =$750, 1.5"=$865 and 2"=$1044... I didn't price the end fittings, but it seems to me from those prices that it would be as cheap or cheaper to do multiple runs of 1" as it would be to do the over 1" sizes... (and your rough rule above suggests that 3x1" is going to give about the same performance as 1.5")

Gooserider

Hmmmmmm.......looking at a couple hummingbirds fighting over the flowers outside my office window and thinking that the flowers will be covered in snow only 90 days from now...............

But I digress....the flow rates listed above are for copper tube. steel piping will be about 10% more and pex will be about 10% less. Personally I avoid anything over 6GPM in 1" pex due to head issues and having to go with high head circs. 12GPM is about max for 1-1/4" and 19 in 1-1/2". Beyond that you get into 26-99, 0011 or 1400 series Taco circs which are 3x the cost to buy and operate. A 15-58 will move enormous amounts of btu's through a properly designed, low head system.

As for me I would much rather handle and pipe up a single line than two or three. Sometimes space simply doesn't permit anything more than that. I sell Viega O2 barrier pex in my shop/store for $218/100 and it baffles me why wholesalers and supply houses don't stock it. 1-1/2" tube is only $2.62 in 100' rolls.

I also tossed the idea of using 3 x 1" if I extend by run to 315' (each way) but with 1.5" at $2.62 handling 1 pipe seems to be much easier and will be easier to insulate. Heaterman are you limited to 100' lengths or is it possible to get larger lengths, maybe even cut to fit at 315'. If I had to splice at 100' intervals, does that affect the head drastically. Will the 26-99 circ still work if I go the longer distance with the 1.5"?

 

[rkusek]

I'm leaning toward the 315' length now because it will come into the basement right into the utility room instead of the opposite corner of the basement where I would have been creating more work for myself to deal with later.