old Bastian-Morley boiler and White-Rodgers valve

pogg

We have an old Bastian-Morley boiler for the hot water heating system in our house which has been in place since 1956. 387,000 BTU/HR input and 309,600 BTU/HR output.I have replaced most of the parts for the Bell & Gossett pumps and the automatic pilot flame sensor myself. White-Rodgers diaphragm valve (type 2691, 25 Volts), and automatic pilot type 3046-5.

My concern is regarding the bleed tube (next to the pilot flame). When the boiler fires up, there seems to be a large yellow flame from the bleed tube which produces quite a bit of soot inside the access flap.

Someone told me to just plug the bleed gas line. Not sure that this is a good idea. Is it possible to fix this, or is it possible to retrofit a more modern gas valve and pilot assembly that would be safer and more efficient?

Mike Kusiak_2

Diaphragm valve bleed

Does the gas escape continuously from the bleed while the boiler is firing, or only momentarily when the gas valve is first switched on and the main flame ignites?



It is normal for a small amount of gas to escape momentarily when the valve is switched, as there is gas trapped in the upper chamber of the valve behind the diaphragm. For the diaphragm to move and the valve to open, this trapped gas must be released which is accomplished by the bleed. You definitely cannot plug the bleed as the trapped gas will then not allow the valve to open.



If however, gas escapes continuously while the boiler is firing, then there is definitely a problem with the valve. Either the diaphragm has a hole in it, or the pilot valve is failing to close completely. Either situation requires the valve to be replaced.



Here is a link to a earlier posting regarding replacing an old diaphragm valve setup with a modern redundant dual seated valve as now required by code:



http://www.heatinghelp.com/forum-thread/132316/Dual-Seated-Gas-Valves-Redundant-Valves



You have a pretty big boiler, and a redundant single valve may not be available with enough capacity, in which case you may have to go to a commercial type gas train with two separate gas valves to meet current code. I am sure Tim can advise as to what is the best way to update your existing system.

pogg

valve bleed

Thank you for your reply Mike. That information and explanation about the valve bleed is very helpful.



Yes, it would seem that there is gas escaping constantly while the boiler is firing. There is a continuous yellow flame from the bleed tube while the boiler fires. As soon as the boilers shuts off, the flame goes out of course.



Sounds like I will have to replace the valve.

Tim McElwain

Yes and as I posted elsewhere here

on HH that valve is a bomb waiting to happen as it has a manual operator which allows the valve to run wide open when it is put to manual with no safety controls whatsoever other than a relief valve which hopefully would open and relive the excess pressure in the boiler.



You will need a gas valve of higher capacity as you are outside the range of residential size gas valves. A valve 1" by 1" will probably handle your requirements and the pilot will also need to be changed. I would definitely recommend a professional who is well versed on doing such a retrofit.

Cramwell

I also have an old Bastian-Morley boiler with a White-Rodgers diaphragm valve. The challenge I am having, however, is the boiler not wanting to fire when the outside temp reaches aroud 20 deg and lower.

One of the questions I have is the setting for the White-Rodgers hydronic Control seen in the first picture. Sometime ago, I had changed the temp setting inadvertently not noting the original setting. As you will note, there is a red marker just beneath the 220 deg. mark. Is that where the setting should be?

To sometime fire the boiler, I depress the plunger seen in the middle picture. However, this is most oftenly success when the temp is above the 20s. The third picture is the white-Rodgers diaphragm valve.

Tim McElwain

That middle valve that you push down is the safety valve for the system which has a thermocouple screwed into the bottom. Make sure the thermocouple is screwed in finger tight and a 1/4 turn. Then you will need to trouble shoot by taking millivolt readings or have a tech come in and do that. That is a fairly old system so you may need to upgrade to a modern gas valve system which will still allow you to use a thermocouple. A Honeywell VR8300A gas valve would do the job.

Tim McElwain

If you want to know how to troubleshoot thermocouples go up to "Before you ask" and open it and then click on the second "here" and look for Tim McElwain it is there.

Cramwell

Thanks, Tim!! What about the hydronic control, what should be the temp setting? Is the red marker beneath the 220 deg where the setting should be?

Tim McElwain

Looks good as you have it around 180 to 200 is normal as long as everything heats adequately.

Cramwell

Thanks, Tim!!