Dunkirk question

bml207

I have a Dunkirk boiler (PVSB-5, I think) that was installed using only one boiler tapping. The installation does meet the minimum specifications in the installation manual but there is a question of the steam quality being produced. (See previous thread, Venting behavior at startup).



Does anyone have any experience with Dunkirk boilers using only one tapping? Should I have it re-piped when the weather warms up? Thanks!

Rod

Pictures

Hi- It would help if you could post a few pictures of your boiler and the attached piping.Take the pictures from back aways so they include the boiler and piping this allows us to trace out the piping. If we need to see more detail we can then zoom in.

- Rod

bml207

Pictures

Here are a few pictures of the boiler. I know the near boiler piping needs insulation. The main itself is lightly insulated.



Thanks for the help.

cn30

Dunkirk

I have a Dunkirk PVSB-7, which has a couple more sections than yours, I think, and it is also piped with just one tapping. It works fine. I wouldn't worry about re-piping yours to use two tappings unless the near-boiler piping needs to be fixed for other reasons.

JStar

Steam

There is always a great benefit to adding the second riser. You will cut the exit velocity in half, which is a good thing. Especially with this style boiler. It needs all of the help it can get to produce dry steam.

bml207

One for, one against.

Out of curiosity, what 'style' boiler is a Dunkirk, i.e. why is it more important to use two risers here than on other boilers?



Also, do you think it might have something to do with my loud, brief hiss right after the boiler fires?



http://www.heatinghelp.com/forum-thread/144755/Venting-behavior-at-startup



Thanks everyone.

todd_ecr

One tapping or two

One tapping is acceptable with the PVSB-5, however like Jstar said, 2 is better because it will cut the velocity of the steam leaving the boiler. You could also end up with a water line that tilts towards the side with the tapping. This may cause wet steam to leave the boiler on the tapping side, and a low water line on the low water cutoff side.



I like to see any of our boilers 150,000 BTU and up use both tappings.

The Steam Whisperer (Formerly Boilerpro)

Style

The Dunkirk PWSB essentially has a very small steam chest for water/steam separation within the boiler.  In  addition, the connecting nipples between the sections are only 2 inch, so the larger 2 1/2 inch tapping probably offers little performance benefit because the velocity of the steam moving laterally inside the boiler towards the exits are extremely high.  A good header is probably extremely important on this design in order for efficient, dry steam to be produced.  When these boilers are running, you can hear the water moving up the risers.  Once the boiler runs for awhile and the water line drops, there is a lot more room for steam separation, and the noise goes away.

Also, a tip on installing these...do not follow the instructions for installation of the skimming port.  Installed according to instructions the bottom of the skimmer is below the level of the connecting ports in the boiler, so you only end up skimming the end section.  Bushing the skim opening down to 1 1/4 on the tee, will raise the skimming level up so all the sections will be skimmed.

bml207

Re-pipe

Thanks everyone. It sounds like I should have the piping redone in the spring. What would be considered gold-standard installation for this boiler? I only intend to get this done once, so I want it to be as close to perfect as possible.



Thanks for the tip on the skim port; no wonder it took me so long to get the waterline to be reasonably steady. I always wondered where that water noise was coming from.

The Steam Whisperer (Formerly Boilerpro)

Here you go

this is one I did several years ago

bml207

Thanks

Thanks for the help. I'll try to get Gerry Gill to come down this far south to do the work in the spring.

Charlie from wmass

taking the supplies off

at separate places will do you a lot of good, I would say even more than using two risers, if I had to choose. The steam is being asked to go awful fast up that single 2" riser off the header. The header looks to be 2 1/2". Is that correct? using 2 risers and seperating the supplies would be even better.

The Steam Whisperer (Formerly Boilerpro)

You certainly couldn't get any one better than Gerry

.