which coal boiler to get

I agree with both Sting and Yanche about the size of the pipe, BUT from a practical standpoint, the 1" pipe is more than adequate.. The upgrade of the circulator pump to push hot water through a 1" pipe compared to a 1.25" or 1.5" pipe is minor, in fact if you want to push the higher volume through a larger pipe you would need to upgrade the circulator pump for the larger pipe, just like you upgrade the circulator for the higher 'head' or flow resistance through the 1"pipe.

A standard cartridge pump burns about .8 amps.. these are rated at 1/25 hp.[Taco 007,Grundfoss 15-42etc] The next size up burns 1.7 Amps, and is rated at 1/12 HP..[Taco 0011, Grundfoss 26-96] I have absolutely no problems pushing ~160K BTU through a 1" Pex-al-Pex pipe with the 1/12HP pump. My pipe runs are 150' long.

The cost of larger Pex pipe is prohibitive, as is the cost of Copper, and the inflexiblilty and potential leaks of iron pipe and pipe joints.. The vast majority of outdoor wood boilers and remote heat units use 1" Pex-al-Pex, for it's strength and Oxygen barrier.

If you have decided on the BTU capacity of an S130 or similar output boiler, you will do fine with 1" pex-al-pex.. 1.25" Pex is available, but is not available in Pex-al-Pex.. this is important and the additional cost is about double..

For about $5 per month extra electricity, I just use a more capable pump.. works great.. The cost of the pump over a 'standard' pump is also minimal.

Greg L

And the debate goes on..

I will add a data point about pipe size/pump size. My AHS 130 is located in an outbuilding and the pipe run between the coal boiler and the oil boiler in the house is about 130 feet (each way). I ran 1 inch Pex Al Pex pipe and use a Taco 007 pump for the loop betwen the coal boiler and the oil boiler.

I run the coal boiler at 160 degrees set point and had no problems heating my home this winter--heating about 3500 square feet.

On the use of the PVC electrical conduit. You can not normally mix 110/220 volt supply lines with 24 volt control lines in the same conduit. The exception is if all lines' insulation are rated to the max voltage, i.e. 600 volts in the example. But if you do so the box your control voltages go into must also be rated for 600 volts. This is not the case with anything you would be using to control a hydronic system. The solution to meet electrical code it to run two conduits.[/quote]

1. there is no section in the electric code that addresses voltages under 30 volts( control voltages).
2. The code states that the insulation must be enough to cover the combined voltage values. In this case, 220+ 24=248volts. Wire is insulated in different classes. The minumum is 300 volts. The next higher is 600 volts. Control wire is rated at 300volts. It is a rating thing but in fact almost all control wire produced currently is actually coated with 600 volt insulation. Unless you are running a subfeed for a panel to your building a 3/4" will handle most anything you have in mind.for a coal boiler in an outer building. LSWITT,,,,,Let's see whom I'm talking to. Scott

What? 120 240 right hand over left eye dont look into the light and then what?? But keep it comeing I am listening .Thanks Brian

Thanks LSFarms I am listening.Brian

To keep the wiring simple, these are the wires that I would run from house to out building.
1. 4-#14 wires. green,white,black,red. Power for the boiler(black) and an additional circuit for lights,recepticles, whatever(red). That's two 15amp circuits. Or 3-#12 instead to give one 20 amp circuit.
2. 6-# 18 wires, three pair. One pair to use as a T-T jumper for summertime domestic water operation. Two pair for spare.
You can make it much more complicated but this is simplistic. Use thhn wire sold at the Depot or Lowes. Have them cut to length. Add extra on to measurement as contrary to what they say, there is no wire stretcher. Hope this helps. Scott

Another factor to consider when terminating 1-1/4 pex is the crimp tool. unless it can be rented it is a large cost. I tend to think that the larger size pex would only be needed if you were taking the max amount of heat available off your boiler. Doesn't that tend to reduce the efficiency somewhat running the boiler that high? Scott

stokerscot wrote:1. there is no section in the electric code that addresses voltages under 30 volts( control voltages).
2. The code states that the insulation must be enough to cover the combined voltage values. In this case, 220+ 24=248volts. Wire is insulated in different classes. The minumum is 300 volts. The next higher is 600 volts. Control wire is rated at 300volts. It is a rating thing but in fact almost all control wire produced currently is actually coated with 600 volt insulation. Unless you are running a subfeed for a panel to your building a 3/4" will handle most anything you have in mind.for a coal boiler in an outer building. LSWITT,,,,,Let's see whom I'm talking to. Scott

Well, I'm no electrical code expert but here's how my master license electrician friend explained things to me. I wanted to run 120 volt THHN lines and 2-conductor thermostat wire in the same PVC conduit. The insulation on the thermostat wire was not as good as the THHN, perhaps it wasn't even marked. Now both were going to a Honeywell R845 circulator control relay. That box has two sections, the 110 volt part and the thermostat terminals part. They are isolated by some stiff cardboard. I was told the problem was that the lower unknown insulation rating on the thermostat wire could cause under fault conditions in the common conduit, to feed 110 volts to the low voltage thermostat portion of the relay and by extension to the thermostat on the wall. That was the No, No. My solution was to run two PVC conduits.

stokerscot wrote:Another factor to consider when terminating 1-1/4 pex is the crimp tool. unless it can be rented it is a large cost. I tend to think that the larger size pex would only be needed if you were taking the max amount of heat available off your boiler. Doesn't that tend to reduce the efficiency somewhat running the boiler that high? :) Scott

opposite

When you use 1 inch pex - you need to run your boiler hotter so you have a higher charge of energy in the water your pumping - or you have to pump even harder. Remember the liquid is the vehicle of energy transfer.

You can transfer things in a 4 foot trailer easier than you can in a wheel barrow but if you work faster with the wheel barrow you can do the same job

Same goes with pipe loops - you can transfer the same amount of energy with a 1 inch pex or a 1-1/2 inch pex line but by volume you can transfer the energy of 140 degree water with less effort in 1-1/2 inch loops - than you can transfer 170 degree water in 1 inch loops
with the same end result. --> the house is warm and that is the goal after all - no mater how its achieved

you guys run your coal boilers hot like chunk wood burners do - I run mine cooler to use less fuel. You could too but coal is cheep for you. At some point when coal gets expensive - you will look for ways to lessen the pounds per hour used. Running a cooler appliance is one way. Plus circulating cooler water in your load loops forces you to circulate the load loops longer - that leads not only to less expensive operation but a more comfortable environment - less like the bang bang - on / off scorched air heating methods and more like radiant heating.

but there I go again with my off the wall wet techniques.

Well, I don't know you so I can't say if your my friend or not. But I'm a master licence holder in the city of albany new york. Very few licences are issued in the capital of new york. The requirements are rather stringent. The first one being a 10 year period of servitude with another Albany master electrician. In years not far removed , I would have agreed with your friends statement. Due to increased UL listing practices, very little wire is less than a 300 volt rating. Almost all control wire is actually manufactured with 600volt insulation. The UL will only give control wire a 300volt listing. None with a UL 600volt listing. Older wire will have less rating. If all thhn is used there is no need to run a second conduit. I can state this with confidence after installing just short of 650,000' of "control wire" in the last year. Scott

Sting,seems like you and I agree on most things but are still so far apart on others. Correct me. 300' of 1" pex contains appr. 45 gallons of fluid. 300' of 1 1/4 contains roughly 83 gallons of fluid. How do you figure it would be easier to push/pull almost twice as much fluid? My head tables indicate that it would take 2 cartridge pumps to move that amount efficiently. Scott

Scott, we are all friends here. It's not a trick question. I'm a retired EE and spent my entire life designing electronics for unmanned spacecraft. There was no incentive to get a professional engineers license so I never did. In retrospect I regret that choice. I have the utmost respect for the licensed trades people, especially those that achieve the highest level of certification. I sure hope you had apprentice help in pulling 650,000 feet of control wire.

Scott, What you are missing in your pumping analysis is that in a closed pumping system there is no static head. It doesn't matter if it's one, two or three stories. What matters is the resistance to flow by the pipes, valves, fittings, etc. Each of these resistances are added up and converted to "feet of head". Once you known the system resistance you look at the pump curve and read the flow rate. Want more flow, for the fixed resistance? Pick a more powerful pump. Or reduce the resistance by using a bigger pipe size. The volume of fluid just doesn't matter in closed systems.

stokerscot wrote:Sting,seems like you and I agree on most things but are still so far apart on others. Correct me. 300' of 1" pex contains appr. 45 gallons of fluid. 300' of 1 1/4 contains roughly 83 gallons of fluid. How do you figure it would be easier to push/pull almost twice as much fluid? My head tables indicate that it would take 2 cartridge pumps to move that amount efficiently. Scott

its not just me
http://www.heatinghelp.com/shopcart/pro ... egory=2-14
page 66 and 67

Design flow rates for hot water heating
These are "TROUBLE FREE" rates but as I have said and others have pointed out - anything is possible in a wet system

Its all about how efficient you wish to run with the equipment you have and at the cost of operation that you comfortable with.

I know - this is like asking a Ford guy to accept my GMC - but we both get back and forth to work don't we?

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