circulators etc.

leonz

I am in the middle of planning my coal stoker boilers plumbing repair/upgrade after the heating season is over.

The near boiler piping is going to be changed to black iron pipe from copper.

The propress fittings will be removed with the copper and I will tell you why; the domestic coil propress fittings attached to the domestic hot water coil blew apart and ran my well dry in the middle of the night several years ago.

I need to fix the circulator set up in my system as the B+G NRF 25 set at speed 1 which is 12 gallons per minute is too much flow for the 225 feet of 3/4 baseboard.
The NRF 25 model was used because that is all the supplier had on a saturday afternoon when the circulator died on me.


SO here is what I am thinking of doing:

1. Replace the NRF 25 with an 8 gallon per minute flanged circulator with an internal check valve. The circulator would preferably be a small "00" TACO with the internal check valve and LED operating light

2. replace the near boiler copper plumbing with black iron pipe to the point where the one inch copper meets the two 3/4" copper lines feeding the two heating loops.
The solder joints are corroding and I would rather do the repair before I have another leak.

As Dan has said "Be the ball when it comes to a tee and see what happens".

My thinking is that I can cut out the copper Tee and then plumb in black iron to the point where a black iron tee would allow the plumbing in of the circuit setters and then attach the 2 circuit setters to the two heating loops using brass threaded to sweat unions.
I have had the heating system develop a pressure gradient (vacuum of 5+ Hg) when I found the heating loops were not working well and the steel compression tank was only half full of water rather than 2/3 full.
I tightened up the packing glands on the sight glass two years ago and that seemed to help along with bleeding the higher copper line feeding the heating loop. There are no visible leaks in my system.

3. purchase 2 B+G 3/4" threaded circuit setters to meter 4 gallons per minute of flow from the new circulator to the 2 heating loops.
a. add a second vent at the top elbow location to vent more air as there was air in the heating loops and also in the boiler drains that were installed to purge the loops of air when they installed the coal stoker boiler.
a1. I am not sure but the air locked condition may have been pulled from the steel compression tank as it is the ceiling on the laundry room which is the highest point in the system. The heating loop is all on the same floor at ground level.

4. add a 2 gallon bladder tank to the domestic hot water coil on the out/hot delivery side of the domestic hot water coil and replace existing copper with L grade copper and use lead free brass union fittings to connect the copper to the domestic hot water coil.
5. replace the existing mixing valve that was soldered to the out connection of the domestic coil with a threaded mixing valve using bronze fittings

=======================================================

Option two would be to just replace the existing NRF 25 with the new flanged 8 G.P.M. circulator with the internal check valve and then wait for the next heating season and save my money to fix the domestic hot water coil in the coal boiler next year.

The first time this happened I tightened the packing glands on the sight glass a 1/4 turn and added water back into the steel compression tank and then drained more water out to obtain the correct air to water ratio and the system corrected itself as it heated the home.
This last time I found air in the pump module where the boiler drain comes off the top of the boiler, trapped air in the overhead line going to the main part of the house which I bled out.
The circulator does not appear to be leaking through the seal so that as thought is nill.

I have lots of pictures of my system and I can post them.

AS a normal state of operation the boiler will reach 180 degrees Fahrenheit high limit and the water in the system will expand of course and the steel compression tank will fill up further and fill the sight glass and the system pressure will reach 8 pounds or more in warmer weather. In cold weather the system will have zero pressure and the water level in the steel compression tank will remain stable.

The dump zone for the house is the 225 foot long heating loop. Adding a garage heater to have a separate dump zone would work well and eliminate the need to open the windowstats.

I probably should have invested in a 30 gallon steel compression tank in the overall scheme of things for this boiler. I can always add one I guess to assure the system pressure stays at zero P.S.I.G.

I have learned a lot about hydronic heating and living with a poorly installed system in the last 5 years. I would replace all the baseboard with cast iron radiators and add five times the thermal mass if I was able to do it.

Any help, suggestions, ideas, "you stupid kid" echo's are welcome.

For now investing in a new 110 volt single phase flanged circulator with an internal check valve may be the best option to prepare for next years heating season.

It would be fun to experiment with the steel compression tank in an upright open to air expansion tank design where there would be no circulator, the overflow would be piped to the laundry tub and the system would move the hot water through the heating loops by simple gravity as all the baseboard heating loops are on the one floor of this house and the boiler sump is on the same level.

The heating system for this house had an open to air saddle tank(horizontal tank) hanging in the ceiling above the boiler with two heating loops and never gave us a bit of trouble and and knowing what I know now I would have never let them take it down when they installed the hand fed wood and coal boiler.

The open to air saddle tank had a glass sight gauge to monitor the fluid level in it and did not use a bladder tank for the point of no pressure change exactly like the current system.



Dan, I still laugh about the Red Flash Boiler with the No 10. smoke story.

Leon

pecmsg

the domestic coil propress fittings
attached to the domestic hot water coil blew apart and ran

Something else happened. Not inserted properly, something. No way a pro-press fittings can "Blow Apart"!

leonz

They blew apart/separated that's all I know.

GroundUp

There is no such thing as an "8 GPM circulator", and the NRF-25 you have on speed 1 is flowing nowhere near 12 GPM through a 225ft loop of 3/4". It's closer to 4 GPM, right where it should be. Without multiple circs in parallel, an IFC is useless

mattmia2

If i'm reading right you are using a conventional compression tank and automatic air vents. That won't work right, the system needs to be arranged to return the air that works its way out of the tank back to the tank. Unless there is something unique to the wood boiler system, having 0 psi static pressure can cause a number of problems like air elimination and pump cavitation.

I assume the tankless coil has a working pressure relief valve on it.

You could add a buffer tank to the system to get more mass to store excess heat and even out the heating.

leonz

Nope, nope, nope; I have a coal stoker boiler.
I have a steel compression tank of 15 gallons capacity with no bladder and it has 5 gallons of air and 10 gallons of water. A steel compression tank cannot work correctly if automatic air vents are used and I do not have any in my system.

I have an airtrol valve in the base of the steel compression tank to divert microbubbles to the water in the compression tank where the eventually dissolve into the air blanket and the cooler water falls back into the piping and then into the boiler

The tankless coil does not have a relief valve and it is not being used currently.

I am pumping away from the top of the boiler.
I have been thinking about adding a buffer tank for a long time now.

I lack a 2 gallon bladder tank for my domestic coil and that is on the to do list.

Robert_25

pecmsg said:

the domestic coil propress fittings
attached to the domestic hot water coil blew apart and ran

Something else happened. Not inserted properly, something. No way a pro-press fittings can "Blow Apart"!

My guess is the coil was valved off without a relief valve or expansion tank.

Robert_25

2. replace the near boiler copper plumbing with black iron pipe to the point where the one inch copper meets the two 3/4" copper lines feeding the two heating loops.
The solder joints are corroding and I would rather do the repair before I have another leak.

You might trade some green leak-free solder joints for a leaky threaded joint. If you just have some surface corrosion on the solder joints, it is likely caused by flux residue that was not cleaned up at the time of the install. A rag with HOT water should remove any remaining flux, and you can shine things up with some steel wool or even a Scotch bright pad.

As for the circulator, the NRF25 is likely fine for your system.

mattmia2

Properly made solder joints aren't really any more likely to corrode than the pipe.

leonz

Robert_25 said:

pecmsg said:

the domestic coil propress fittings
attached to the domestic hot water coil blew apart and ran

Something else happened. Not inserted properly, something. No way a pro-press fittings can "Blow Apart"!

My guess is the coil was valved off without a relief valve or expansion tank.

=================================================================

The coil was open to flow at all times and worked fine for 2 years before that during the annual heating season.
Both internal boiler mounted circular domestic hot water coils and side arm flat plate heat exchanger domestic hot water coils depend on the hot water tanks blow off valve. I will be installing a 2 gallon bladder tank when the time comes.

hot_rod

From the info you supplied it sounds like the circ is sized close enough? If you add two circuit setter you can dial it into exactly the flow rate you need.
I'd focus more on the buffer tank addition in your repiping. Really no sense in dumping heat if you have some buffer to store it and use it as needed. It could make the coal boiler run at a more comfortable, possibly more efficient condition.

No harm in adding a DHW expansion tank, certainly if there is any backflow or check in the plumbing.

The system will work better and remain air free if it is sealed and pressurized. 12 psi cold, may bump up to 18- 20 at 180F, no reason I can think of to see it fall to 0?, regardless of the type of expansion tank you use.

I feel a diaphragm tank and a microbubble air purger is the best method for air removal. Properly piped the Airtrol fitting does some air elimination, not to the degree as a good microbubble type.

leonz

Hello Bob,

Thank you very much for your valued comments.

I am at the point where I believe a New Horizons 425 gallon insulated hot water storage tank to act as the dump zone/buffer is the best way to handle this too. The stoker would burn even less fuel.

I could mount the circulator on the buffer tank moving the pump module to the buffer tank and feed the buffer tank from the top tapping of the stoker boiler routing the 1 1/4" pipe to the bottom tapping in the end of the storage tank.

My line of thought was that I could more easily use the 15 gallon steel compression tank as an open to air expansion tank by standing it up and purchasing a longer sight glass for the side tapping's too.

I went back to an steel compression tank with an airtrol valve because of the problems I had in the past with first bladder tank system with the hand fed wood and coal boiler I had in 1981 as it was losing water some how. I no longer have issues with water loss.

The open to air saddle tank with the sight glass that was hanging in the ceiling in this house in 1978 never ever gave us one problem ever and the two loops did not need to be bled.
I should have told the plumbers to leave it there when they put in the hand fed boiler but I did not know enough about hot water heating then as I grew up with steam and scorched air.

Leon

wesPA

I ended up using a buffer tank (119gallon) on my system when I installed it 5 years ago and I am glad I did. My coal boiler is hand fired so it really helps even things out, my tank temperature can fluctuate quite a bit and I mix out of the tank to the house loop. (cast iron radiators) The tank essentially becomes the dump zone if needed.  I haven't had any issues using a standard bladder style expansion tank, although I probably should have went with a larger volume tank with the water volume in my system. 

leonz

Hello Wes,

Thank you very much for your comment.

like your design I would like to push the hot water delivery and
the dump temperature water of 190 degrees Fahrenheit water
through the 425 gallon New Horizons tank and then into the
heating loop through the new circuit setters I will be buying
and set them at 4 gallons per minute.

I wish I had cast iron radiators of course to begin with.

I would be able to use the summer stoker temperatures of
140 low 160 high more easily and eliminate out fires from
the lack of heat calls in warmer heating months.

I am waiting on the Wessels Tank folks for an answer about my
tank question and I will waddle on after that.