which coal boiler to get

Yanche! Impressive credentials. Just my luck I pick an argument with a rocket scientist. Just kidding, no offence meant. Seems like I get drawn in by the best of them. Engineers! But,,,,, as in keeping with the engineers creed, overbuilt piping systems just don't work for us blue collar folks. When it comes down to it, cost plays a big factor in design of these systems. While my "thermodynamics degree" from the USN shouts out that you and Sting are correct with your information, the jack of all trades(master of some) in me screams that 1" pex will flow plenty of heat to all but the largest installs. And accomplish that very easily. There are too many people here saying so. I think that the money saved on the smaller size pex would be better spent on another part of the system. For me and others, overpriced heating costs were the driving force to find this site. In keeping with that line of reasoning we should define a couple categories for the new installers. The enough to get the job done line and the better if possible line. Personally I would run 2" pex and three 3/4" conduits if possible. Third being used for the internet access to the microprocessor to run the boiler. And a TV Scott

It's a cost factor. If 1.5" pex-al-pex was available, much less at a reasonable cost, then I too would say it is the way to go, but with the lack of available products at a reasonable price, the 1" pex-al-pex is the way to go.

I agree that you can move more heat with the larger pipe, but the proof is in the application. I think my system should be marginal with 1" pipe, but it isn't .. even when I have all three zones circulating, and domestic hot water being heated, my single 1" pex loop, 150' each way, so a 300' loop does just fine,, it transfers the full amount of BTUs needed..

As for the crimp tools, for the 1" pex, I use a compression fitting with two rubber O-rings, and a threaded compression loop on the outside of the pex. I've had zero leaks, and you can dismantle the fittings and reuse them.. The one-time crimp tools are most common for the smaller 1/2" and 3/4" pex used in domestic water piping, at least in my area this is what I see.

Greg L

stokerscot wrote:Sting,so why aren't we using 4"? Twed vewy sofwy,I'm hunting wabbits. Scott

Because the trouble free design flow rate of 4 inch steel pipe is 300 GPM and there are no loads discussed here or boilers for that matter that large that we chat about.

Shoot straight now!


I am more of a duck that a rabbit - its a wet heating guy thing!

WE --- may be bogged down in two schools of thought here that simply dawned on me again - I forget so much - its the mad cow thing beginning. But you can look at this like a heating guy or a plumber and thats two very different worlds. The key is a commingled education from successful dead guys who were good at each. And a lot of reading.

another analogy:
Plumbers zone with pumps - heating guys zone with valves.

I agree that 1 inch PEX with a larger pump will work. What bothers me is when you look at the overall system design you have made the piping the system limitation. Because of cost and availability considerations 1 inch PEX is proposed as the universal solution, independent of boiler size and piping distance. Let's say in Greg's case the PEX is limiting the delivered BTU. The heating of his house meets his expectations. Then it's likely his AA 260 is to large a boiler, because there is no way 260,000 BTU can be delivered via 1 inch pipe. So the BTU needed to heat his house must be less and perhaps the smaller and less expensive AA 130 would be a better choice. At full or near full load a boiler will operate more economically than a boiler operated at half load. Unfortunately we can't judge if Greg's boiler is two large for his home by it's duty cycle because he also heats his shop with it.

So ,,, how much heat will a 1" pex run at 180 degrees. if the run is from 1 boiler to another boiler around 150' distance. Scott

stokerscot wrote:So ,,, how much heat will a 1" pex run at 180 degrees. if the run is from 1 boiler to another boiler around 150' distance. Scott

Again we are confusing energy and flow, but the parameters are simple enough: 180 degree water or 140 degree water - each must produce a delta T on the supply and return appliance ports, and must do so relative to degree day load, and that changes daily during the season, so supply temps should also - but circulation should not have to - and thats trouble free design flow! You tend your boiler and your mixing valves to match load demand, not the other way around.

Ill post the short cut from page 65 of my remaining "book of golden rules"

"Assuming the system will work on a 20-degree F. temperature drop, you can arrive at the proper flow rate by dividing the net Btuh load by 10,000. For instance, if the net heating load is 40,000, the proper flow rate is 4 gpm"

lets reverse engineer that to address your question:

From the parameters - the "Maximun, Trouble-Free, Design Flow Rate for Hot Water Heating" of 1 inch is 8 GPM - the net heating load best supported is


Buehler??


Buehler??

80,000


Easiest way to figure the pump head in that loop - again based on the maximum flow through the system

and the question is for 1 inch pex so 8GPM is the goal but we need to know what pump to achieve this goal.
1. Measure the "Longest" ( highest pressure drop) piping circuit in feet
2. Multiply this by .06
3. The answer is in feet of pump head.

And how many btus per foot of baseboard radiation? Scott

stokerscot wrote:And how many btus per foot of baseboard radiation? Scott

Longest "Safe" Length of Continuous Baseboard Loop

(Element Only)

1/2" 25 Linear Feet

3/4 " 67 Linear Feet

1" 104 Linear Feet

1-1/4 177 Linear Feet

WE can also dive into Equivalent Direct Radiation (EDR) here to answer the question but that need to be addressed in concert to the part number of the Baseboard in use:

For Hot Water: One Square Foot EDR will put out 150 Btuh when the average water temperature is 170 F.
Since I recently did some Cast- Iron Baseboard _ I still have the spec, It was 10 inch hi - 2-1/2 wide and the Sq. Ft. Per Linear Foot was 3.4

stokerscot wrote:So ,,, how much heat will a 1" pex run at 180 degrees. if the run is from 1 boiler to another boiler around 150' distance. Scott

My calculations indicate it will be about 60,000 BTU with a Taco 007 pump. More details to follow once I can get the correct values for the specified conditions.

So if 1" will run 104" of baseboardthat means that you using 15,000 btu's or somewhere close to that. That's alot of baseboard for one loop! But a huge waste of the available heat that will flow thru 1" pex. Wouldn't it be effective to run several loops as discussed in your book using the primary secondary loop method that you are alwys pushing . According to your figures it would be possible to feed enough heat thru 1" pex to supply between 300-400 linear feet of baseboard radiation. Did I catch a wabbit or a duck Scott

stokerscot wrote:So if 1" will run 104" of baseboardthat means that you using 15,000 btu's or somewhere close to that. That's alot of baseboard for one loop! But a huge waste of the available heat that will flow thru 1" pex. Wouldn't it be effective to run several loops as discussed in your book using the primary secondary loop method that you are alwys pushing . According to your figures it would be possible to feed enough heat thru 1" pex to supply between 300-400 linear feet of baseboard radiation. Did I catch a wabbit or a duck Scott

No _ I fully expected you would see it like that - so I left the door open for you to slam it to me

WE all need our hobbies

Actually an "over sized" radiation as outlined - supplied by the GPM I note - is a very easy system to tend and control - Its very comfortable and smooth to operate and live in. It provides a more even radiation to the room or load by the energy supplied to it, when that energy is supplied to loop via a temperature that produces a 20 degree temperature drop and that water temperature is varied according to degree day load demand. Primary / secondary loops only make it easier to vary supply water temperature by loop load demand.

I profusely apologise. It's not coming across like I was hoping. Sorry. My main point being the original post by Mwolfie was talking about heating 2000 sq. ft. newly built house. Seems like a 1" pex would heat his house just fine IMHO. Scott

I took no umbridge in your statement to the Duck hunt!

Its fun to fool around a little

And I know that until you live with an over sized radiation system that is gracefully driven with low energy fluid - it will be difficult to understand the savings and the comfort of daily living in those rooms.

So Ill just calmly continue to annoy folks with my off the wall heating ideas.


BTW ---- do a heat loss calculation http://www.slantfin.com/heat-loss-software.html on the load before "assuming"

There is something else. The building outside could be large enough to house your emergency generator. Good place to put it. An additional 3/4" pvc conduit in the ditch for future projects probly isn't such a bad idea. $25 per 100' Scott

Sting, in earlier posts the ideas you were putting forth sounded out of line. But after much hashing, I will say your ideas sure carry alot of heat I do get your points, they are sound. Particularly the close t deal. I still think a hybrid system with a line with a close t deal run between the supply and return header is the way to eliminate all the losses from the additional mass being heated, plus it's easy to hook up to an existing system. It isn't fully automatic, but then again most coal boilers aren't. I'm sure I'm about to get spanked, take it easy, it is a hobby we all share. Scott