Boiler "Upgrade" to Jetstream

[graham7226]

Hi I've been reading these forums for a few years, but this is the first time I've posted. I'm "Upgrading" From an old conventional boiler to a new-to-me Jetstream. The Jetstream needs some work and is in the shop now getting overhauled but I need to start figuring out how to install it and was hoping some folks here would be so kind as to lend their experience.

Current setup: Boiler is in the shop, and the water is pumped through 240' of five wrap insulated 1" PEX (Yes, I know that's a long way for 1" PEX, but my house only looses 30,000BTU's hour) to a 60 gallon electric water heater then a variable speed pump injects it into the floor loop.





The Plan: Boiler stays in shop, Piped in 1.5" Black iron to storage. The electric water heater gets removed, and the variable speed injects straight out of the 1" underground PEX loop from the shop.



The big questions I have are:
How much storage? I can get a 500 gallon propane tank fro around $400, and a 1000 gallon for around $600. But space is at a premium and other than burying the 1000 gallon tank outside I'm not sure where I'd put it. Is 500 Gallons enough? As I understand it the Jetstream is rated for 120,000BTU's hour?

Do I need another pump between the boiler and the storage or will it thermosyphon by itself with 1.5" pipe?

 

[woodsmaster]

You will need another pump. 500 gallon should work with that low heat demand, just have to be careful not to overload the boiler. Good choice on boiler, not so good on the underground line. i'm sure there will be significant heat loss to the ground. If the underground isn't in place yet I'd recommend having an insulation contractor spraying foam around it. Depending on amount of heat loss to the ground the 500 gallon storage may not last as long as you desire.
Edit : 1 " is small line to run at that distance. Should work with your low heat demand but will probably need a good size pump.

 

[kuribo]

I would second the opinion on the five wrap lines. That stuff should be illegal....

 

[graham7226]

The Underground lines have been in for a couple years now, running with the old Titan boiler. Knowing what I do now I would have opted for something larger than 1" for that 240ft (that's only one way, so I guess that's closer to pumping 500ft). Oddly though I don't really notice any amount heat loss in the lines from the boiler to the house, that may be because the pump is large (Grundfos 43-75 it wasn't sized for the application I just happened to have a couple of them lying around) or maybe because the line isn't so much as buried as strung through a hill between the two buildings, as such if water ever penetrated the tile it would pretty much have to end up in my house.

 

[slowzuki]

How do you know what the heat loss is going to the house? Measure temp at boiler supply and temp at house supply?

The Jetstream can thermosiphon with big pipe, minimal fittings and elevated storage but you will have trouble getting the last big of the charge, boiler will boil before tank is fully charged. A circulator is a good idea for this reason.

For storage, the infloor means you can pull your storage down much lower than most. I think most Jetstreams are paired with 800-1200 gallons of storage. Could you cut the 1000 gallon in 1/2 and stand the two halves on end? Tri-county in Moncton has good prices on used propane tanks too.

I'd love to see pics of that old boiler cut open if you have them. I'm glad to hear someone do something with it rather than have it sit in my shop.

The Underground lines have been in for a couple years now, running with the old Titan boiler. Knowing what I do now I would have opted for something larger than 1" for that 240ft (that's only one way, so I guess that's closer to pumping 500ft). Oddly though I don't really notice any amount heat loss in the lines from the boiler to the house, that may be because the pump is large (Grundfos 43-75 it wasn't sized for the application I just happened to have a couple of them lying around) or maybe because the line isn't so much as buried as strung through a hill between the two buildings, as such if water ever penetrated the tile it would pretty much have to end up in my house.

 

[ewdudley]

1 " is small line to run at that distance. Should work with your low heat demand but will probably need a good size pump.

But the beauty of in-floor radiant is high system deltaT. Should be able to get a deltaT of 50 degF easily. 2 gpm times 50 degF deltaT times 500 is 50,000 btu / hour. 2 gpm through 500 ft of 1" nominal PEX is less than 4.5 feet of head, which any small pump can handle.

I would recommend leaving the 60 gal tank in place and use an aquastat near the bottom of the tank to activate a pump that replenishes the 60 gal tank from storage. When aquastat falls below (for instance) 110 degF turn pump on, when aquastat rises above (for instance) 115 degF turn the pump off. This will ensure that the storage tank doesn't get mixed down to a lower temperature, which ensures that system deltaT stays high.

Floor loops draw from tank same as ever.

 

[graham7226]

How do you know what the heat loss is going to the house? Measure temp at boiler supply and temp at house supply?

The Jetstream can thermosiphon with big pipe, minimal fittings and elevated storage but you will have trouble getting the last big of the charge, boiler will boil before tank is fully charged. A circulator is a good idea for this reason.

For storage, the infloor means you can pull your storage down much lower than most. I think most Jetstreams are paired with 800-1200 gallons of storage. Could you cut the 1000 gallon in 1/2 and stand the two halves on end? Tri-county in Moncton has good prices on used propane tanks too.

I'd love to see pics of that old boiler cut open if you have them. I'm glad to hear someone do something with it rather than have it sit in my shop.

There are well/thermostats at both ends of the underground pex, one in the house and one on the boiler. Although they are far from precision instruments there doesn't seem to be much of a difference between them when the pump is running.

Tri-province is where I priced the tanks, I'd like to have the 1000 gal one but like I said space is tight and fitting a 15' x 48" tank in the shop would be hard. That's a good idea cutting it in half, but I don't think I trust my welding skills enough for that. I might just break down and buy two 500's they're a little more manageable at 9'x30".

I didn't actually cut the side off, just a 8" x 10" or so hole in the side, big enough for a vacuum, and to reach my arm in. You can see from the picture that the mice really made themselves at home in there. That's all cleaned up and the hole patched the problem I'm having now with it is that between the lack of cross ties, and a couple of the heat exchanger tubes being rotted out, the tank keeps failing my pressure test. I attached an airline to the boiler and filled it to 30PSI. Seems like every time I get one air leak fixed another pops up.I added two cross ties, replaced one of the tubes, and was started on the next when the oxygen on the torch ran out.

 

[maple1]

I got my tanks at Tri-Province also. I'm pretty sure the 500's are 36" x 9-1/2'. My 330's are 30" x 9'.

 

[maple1]

BTW, there are threads on here by Hobbyheater about his Jetstream overhaul(s).

 

[graham7226]

But the beauty of in-floor radiant is high system deltaT. Should be able to get a deltaT of 50 degF easily. 2 gpm times 50 degF deltaT times 500 is 50,000 btu / hour. 2 gpm through 500 ft of 1" nominal PEX is less than 4.5 feet of head, which any small pump can handle.

I would recommend leaving the 60 gal tank in place and use an aquastat near the bottom of the tank to activate a pump that replenishes the 60 gal tank from storage. When aquastat falls below (for instance) 110 degF turn pump on, when aquastat rises above (for instance) 115 degF turn the pump off. This will ensure that the storage tank doesn't get mixed down to a lower temperature, which ensures that system deltaT stays high.

Floor loops draw from tank same as ever.

2 gpm? That sounds manageable. I really don't know much about hydronics, as an Electrician the formulas I learned in school don't do me much good here. I just take a more-or-less educated guess, and when in doubt go bigger. I do know that the pump I have seems to work with that line though, as I am able to bring the temperature up in the water tank even when the floor is calling for heat.

I like the idea of keeping the 60gal tank, I've got it wired up as a bit of backup heat. 6Kw of heat isn't much, but it lets me leave the house alone for a few days when I need to. The reason I was going to remove it is I thought it might be more efficient to use the variable speed pump to mix straight from the underground loop, with the tekmar turning the underground loop on only when it wanted to raise the boiler supply temp.

 

[tom in maine]

This is a wonderful boiler design with great serviceability.
Do you have all the covers and the blower? Looks like it spent time in a damp barn or basement.

 

[ewdudley]

I really don't know much about hydronics, as an Electrician the formulas I learned in school don't do me much good here. I just take a more-or-less educated guess, and when in doubt go bigger

Your electrical knowledge might do you more good than you suppose!

DeltaT is voltage drop. When we see a change in temperature (delta of temperature, deltaT) of some flow of water then we're seeing a gain or loss of energy, same as gain or loss of energy when we see a change in voltage of some flow of electrons from point A to point B.

gpm is amperage. Gallons per minute, coulombs per second; take your pick. With hydronics it's flow of water, electricity is flow of electrons.

Power is unit of energy per unit of time: btu per hour for water, watts (joules per second) for electricity.

So wallop times flow is power. Voltage drop times amperes is watts. DeltaT times gpm times 500 is btu per hour. (500 is just a conversion factor to get us from gallons of water per minute to btus and pounds of water per hour.)

But resistance is much trickier. With wire the resistance stays more or less the same as long as we're keeping the amperage reasonable, but with pipe the resistance varies exponentially with flow. Here's a sheet that explains most everything you need to know to get a handle on flow, resistance, and pumps:

(broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf)

So bottom line is that in-floor and other radiant emitters can give you nice big deltaTs. Any time you have higher deltaT you can use smaller pipe and less flow, same as using smaller wire and lower amperage with 440 V to deliver the same power relative to 200 V.

There's no need for when in doubt go bigger. If you can nail down numbers for maximum heat loss and minimum emitter deltaT then you can figure out what maximum flow needs to be and what maximum size pump will do the job. (Which might not be possible if the pipe is too small.)
,

 

[graham7226]

This is a wonderful boiler design with great serviceability.
Do you have all the covers and the blower? Looks like it spent time in a damp barn or basement.

No I don't have the covers or blower, it may never have had them. As I understand its a prototype, as you can see from the photos there is a bit of a difference between mine and the production model. I'd still love to find a production model but this one will do for now I hope.

The Jetstream is a great design, simple yet efficient, at least in theory. I hope to have some actual experience with it by next heating season. I had run across the rocket stove design and had been reading what I could find about it, with the idea of building a boiler by adapting that design when I ran across the Jetstream on the internet, and realized someone had basically already done it. Since then I've been keeping my eye out for one. Slowzuki had this one stored in his shop only an hour or so away, and the price was right, so I picked it up. I guess he found it in a falling down building, he knows more about its origins than I do.

As mentioned before this one is some kind of prototype and does seem to be somewhat under built, the production models have the corners rolled, mine are welded, and there are several cross ties through the boiler, mine had none. I'm not sure if the upped the steel gauge or not. This one has some issues at the higher end boiler pressure, it's sides are bowed out a bit, so I added a couple cross ties. Even then I had a crack develop in one of the corner welds when it was pressure tested. I'm hoping it will hold up under use.



(Production model is probably Hobbyheater's, I think he singlehandedly uploaded all the jetstream images that can be found on google)

 

[graham7226]

Your electrical knowledge might do you more good than you suppose!

DeltaT is voltage drop. When we see a change in temperature (delta of temperature, deltaT) of some flow of water then we're seeing a gain or loss of energy, same as gain or loss of energy when we see a change in voltage of some flow of electrons from point A to point B.

gpm is amperage. Gallons per minute, coulombs per second; take your pick. With hydronics it's flow of water, electricity is flow of electrons.

Power is unit of energy per unit of time: btu per hour for water, watts (joules per second) for electricity.

So wallop times flow is power. Voltage drop times amperes is watts. DeltaT times gpm times 500 is btu per hour. (500 is just a conversion factor to get us from gallons of water per minute to btus and pounds of water per hour.)

But resistance is much trickier. With wire the resistance stays more or less the same as long as we're keeping the amperage reasonable, but with pipe the resistance varies exponentially with flow. Here's a sheet that explains most everything you need to know to get a handle on flow, resistance, and pumps:

(broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf)

So bottom line is that in-floor and other radiant emitters can give you nice big deltaTs. Any time you have higher deltaT you can use smaller pipe and less flow, same as using smaller wire and lower amperage with 440 V to deliver the same power relative to 200 V.

There's no need for when in doubt go bigger. If you can nail down numbers for maximum heat loss and minimum emitter deltaT then you can figure out what maximum flow needs to be and what maximum size pump will do the job. (Which might not be possible if the pipe is too small.)
,

Thanks for the PDF link, I've got to keep a copy of that in my saved folder. So then if I'm doing this right my 43-75 Grundfos should be pumping roughly 5Gpm through my underground loop?

 

[ewdudley]

Thanks for the PDF link, I've got to keep a copy of that in my saved folder. So then if I'm doing this right my 43-75 Grundfos should be pumping roughly 5Gpm through my underground loop?

That's right. Now since it takes 3.6 times the power to pump twice the flow, it can really pay off to use the smallest pump that will do the job.

In your case if all you need is 2 gpm or less you could go from a 215 watt 43-75 to a 50 watt 15-58 running on speed setting II, or even a Grundfos Alpha/B&G Vario/Wilo Stratos using 25 watts at a lower speed setting. Or if you've got an old 15-58, Taco 007, Taco 008, or similar laying around you could cut back to 75 watts.

In any event there is no need to run the pump constantly. If you can control the pump with an aquastat at the tank, then the pump only needs to run when the temperature at the bottom of the tank drops below a certain temperature that's right for your system, probably something like 100 degF.

(Also there's no return temperature protection in your drawing, which you probably need.)

 

[CaperM]

I bought one of the last Jetstreams in 1994 at Kerr in Truro and still running.It's been a great furnace,I do not have return protection and as yet haven't a problem.Although it probably should be installed on some furnaces.A buddy is looking for a fan motor for his older Jetstream.

 

[tom in maine]

I visited Dick Hill yesterday and we were talking about the Jetstream a bit. None of his original licensees had any return protection. The big difference was that the combustion chamber was refractory on the Jetstream. Dumont and Madawaska. They were very similar to his original design.
The Jetstream is his (and my) favorite variation on the theme.
He told me that his homeowners insurance was cancelled because he heats with woodstoves. Strange world we live in when one of the great innovators of wood combustion gets screwed over by an insurance company.
He does not mind because he saves over $1000 a year!

 

[hobbyheater]

I .A buddy is looking for a fan motor for his older Jetstream.

The vacum cleaner motor or the belt driven blower ?

 

[CaperM]

I am not sure which motor he has, it is an older model. Actually he has 2 older Jetstreams,the last one he bought 15 years ago.This one was siting in the basement,the owner was seldom home and just wanted it gone for $400 dollars.

 

[graham7226]

I am not sure which motor he has, it is an older model. Actually he has 2 older Jetstreams,the last one he bought 15 years ago.This one was siting in the basement,the owner was seldom home and just wanted it gone for $400 dollars.

Lol, he doesn't want to sell one does he?

I'm planning on using an actual shop vac for mine, at least to start.

 

[salecker]

Hi
A local guy i know took his Jetstream out of his house,and it is in his yard if anyone wants it or any parts of it.I can help with getting stuff shipped.
Thomas

 

[BoilerMan]

I never realized that the Jetstream was a pressurized boiler. Always thought the design was meant to be open system. By the looks of the stays and the relief valve I've learned something about them. Dick Hill always ran all unpressurized stuff I believe, 275gal oil tanks in the beginning for storage. Tom?

TS

 

[CaperM]

My friend with the two Jetstreams has the beltdriven fan,and the motor is toast.There could be parts available,I am going check next week.

 

[graham7226]

I never realized that the Jetstream was a pressurized boiler. Always thought the design was meant to be open system. By the looks of the stays and the relief valve I've learned something about them. Dick Hill always ran all unpressurized stuff I believe, 275gal oil tanks in the beginning for storage. Tom?

TS

The Kerr owner's manual I have calls for a homemade tank out of 2x6's and a EPDM liner, with a heat exchanger made from 100' of 1" copper hung inside the tank. So the storage was intended to be unpressurized, at least by Kerr. It makes sense when you look at the price of expansion tanks! The only thing is I wonder how efficient they would be to put the heat in then get it back out. If the tank layers properly I would imagine it would be almost impossible to get all the heat out with an exchanger of that design.

My friend with the two Jetstreams has the beltdriven fan,and the motor is toast.There could be parts available,I am going check next week.

TS

Motors aren't usually that big a deal, as long as it's similar, especially with a fan. Just keep your RPM's and HP close.

 

[Hydronics]

You may want to review Tom's website (Americansolartechnics.com) before you build a tank. A 1" hx is not the most efficient and epdm is not the ideal liner material.