Feed water heaters, and exhaust duct.
September 01, 2021 04:25PM
Feed water heaters, and exhaust duct.

Most feed water heaters are located close to the boiler and in the exhaust system duct.
Other feed water heaters can be in the engine exhaust steam pipe. I have used both in unison and singularly.

Feed waters in the exhaust duct just above the boiler have the highest differential temperature then the engine exhaust steam or location in the duct system.

Attached are some of the feed water heaters I have built and used. I am having a problem finding photos of engine exhaust feed water heaters used on my Steamboats, as most photos are hard copies not digital. ( age related )

The Stanley exhaust system for most Stanley is pretty much the same, just different dimensions and length.

Attached is a drawing for my Stanley EX exhaust system, not shown on the drawing is the whole on the boiler end of the duct. I have attached a photo of this hole. It’s really a flap three-sided cut into the end. This is necessary to relive some of the engine exhaust suction on the boiler. If totally closed you can suck the pilot right out. Running the system you will be able to bend the flap and balance the draft suction.


Re: Feed water heaters, and exhaust duct.
September 02, 2021 05:55AM
Thanks Rolly...

A quick comment is to use the feedwater heater, hot gas exhaust and engine steam exhaust in concert. The steam exhaust and steam blower increase the draw on the burner. I find this very important on my firetube boiler for my steam powered scooter. Without it, the flame is really lazy. I have no performance.

As a new thread I'm attaching my concept again just for reference. As you know, the faster the hot gas flow more the heat transfer.

In this new concept, I will condense some water and collect it in a short drum. This water would go back through the pump and feedwater heater to the economizer. Hot gas from the burner/boiler would exhaust into the feedwater heater on the outside. The steam exhaust would travel counter flow to a reversing nozzle and create draw on the burner through the boiler. A steam blower will also create draw on the burner/boiler hot gas flow.

Attached is another slide I plan to present at the meet. I'm sort of performing a peer review? Note that I'm fond of using the engine exhaust as draw on the burner. Interesting you say that it will pull so hard that the pilot lite goes out.


Re: Feed water heaters, and exhaust duct.
September 03, 2021 10:35AM
Rolly, The small hole cut into the front of the exhaust duct is also really necessary to keep the pilot light lit while coasting down hills. Without the hole, the pilot lite was sure to be out after a long down hill coast with the burner cycled off. The hole provides enough of a steady draft through the exhaust duct to provide an active flow of fresh air for the pilot light to stay lit.
Re: Feed water heaters, and exhaust duct.
September 07, 2021 03:27PM
Here is a steam exhaust feedwater heater I made for the H5. Consists of two helical coils of opposite rotation so that they can nest together. Water is pumped in to the cold end and winds foward to the front of the front of the unit which is sited in a muffler-like can in the steam exhaust. It worked very well and cold water from the tank would enter the boiler at 170-190F. Interestingly the device also acted as a muffler and the exhaust chuffing was quieter when feed water was being pumped. Strictly this should be called an economiser. I also had a double spiral water heater in the smokehood over the boiler.


Re: Feed water heaters, and exhaust duct.
September 10, 2021 06:35AM
That is a nice looking design! Question, is it 4 parallel circuits? Also, does the steam condense in there? BTW, I love H-5's!

In another thread in relation to this thread, thank you for your encouragement. I do plan to put a feedwater heater into my H-5 replica build. It will incorporate all the items I show in my above concept. If I can get that kind of efficiency, it will be very worthwhile to implement.

Rick H, Your engine exhaust feedwater heater is a standard item for the non-condensing Stanley. With it's hot feed water, it adds about 15% performance to the boilers evaporation rate. The collection pit for condensed water in your feed water heater is a novel idea. In a Stanley, the engine's exhaust pulses would most likely blast your water collection pit empty of water in short order. It is worth experimenting with.

Note that I'll be cognizant of the steam exhaust in blowing out the water collection tank. The steam automobile meet is this coming weekend (17 - 19th) and I'll be sketching out some designs as I get ideas by looking at other steam vehicles. I'll be showing my progress as I build...always a pleasure working with you!

Re: Feed water heaters, and exhaust duct.
September 11, 2021 08:30AM
Your drawing is correct. Both my boats used an engine exhaust feed water heater as you show in your drawing, counter flow. My big 35 footer the entire exhaust system was aluminum as the boat and condenser were AL connected to the engine exhaust with steam rated rubber hose. (Galvanic isolator) Fitting for water connection were Stainless steel between the copper and Aluminum also for (Galvanic isolator) The feed water heater was over six feet in length.

All the photos I posted are in fact Economizer, a device that heats feed water using boiler exhaust gases. This is the area of the largest differential temperature. The further you get away from the boiler the lower the differential. I have seen 700 F on 300-PSI boiler exhaust gases, that’s not a very efficient boiler.

On a condensing steam car the engine exhaust feed water heated is a good add. From there you would go into a blast plate oil separator and then to the condenser. David Nerrgard added a Root blower before the condenser to drive a fan for the condenser. If you use Mobil SHC 634 ISO 460 oil, you can do away with a blast plat oil separator or any separator, as the oil will separate from the water on its own.

Economizer, (boiler exhaust gas feed water heaters.)
Exhaust feed water heater, (engine steam exhaust heater)

I used neither on my EX as I wanted to keep it original, I did use an electronic water level indicator as the original was a bucket float indicator. I did keep the bent wire indicator through the dash; Stanley never used a reflex gauge.


Re: Feed water heaters, and exhaust duct.
September 12, 2021 09:26AM
Very nice looking Gage arrangement!
Re: Feed water heaters, and exhaust duct.
September 13, 2021 04:31PM
There were four coils in parallel fed from the cold rear end of the "muffler" via the brass manifold block and exiting at the front. The coils were wound in opposite directions, changing rotation halfway along so that they could be nested together. I made them each from a single length of annealed 8mm pipe on a 2 inch bar rotated by hand in my lathe with a round block fixed halfway along the bar around which the midpoint of each was hooked so that as the lathe rotated the copper pipe was drawn onto the tube. Pegs fixed along the bar regulated the spacing of the coils. I annealed the lengths of pipe by pulling them slowly through a 3 foot long furnace made of firebricks and fired from the output end by a 70,000 BTU gas torch.

The steam exhaust went into the side of the casing at the front perhaps 18 inches from the exhaust manifold on the cylinders and the steam escaped, along with any condensation from the tail of the unit.I didn't make any provision for condensation the be drained from the unit and although there must have been some, it certainly was not a condenser.

Re: Feed water heaters, and exhaust duct.
September 15, 2021 11:45AM
Thanks to all for great feedback. I'll be presenting the attached slides above during a technical presentation I'm giving Saturday morning at the SACA Meet. Please see the zoom invite I'll be posting on the SACA Meet thread. I'll be doing that tomorrow afternoon. I'm traveling tonight and tomorrow to the meet. The presentation is titled a Comparison of Boilers from Serpollet to Chuk Williams LSR. I cordially invite all readers of this forum to zoom in and attend if not coming to the Meet in person.
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All files from this thread

File Name File Size   Posted by Date  
Exhaust Duct.jpg 68.3 KB open | download Rolly 09/01/2021 Read message
DSC_0007.JPG 447.8 KB open | download Rolly 09/01/2021 Read message
Derr economizer.jpg 97.1 KB open | download Rolly 09/01/2021 Read message
Tryall.jpg 30.5 KB open | download Rolly 09/01/2021 Read message
Stanley economizer.jpg 113.5 KB open | download Rolly 09/01/2021 Read message
Marine economizer.jpg 51.2 KB open | download Rolly 09/01/2021 Read message
65-Feedwater Heater Concept.png 140.3 KB open | download Rick.H 09/02/2021 Read message
50-Burner Boiler Flow Options.png 426.3 KB open | download Rick.H 09/02/2021 Read message
Small parallel fwheater.jpg 211.6 KB open | download Mike Clark 09/07/2021 Read message
P2090004.JPG 842.8 KB open | download Rolly 09/11/2021 Read message
water level indercator.jpg 90 KB open | download Rolly 09/11/2021 Read message