Vintage Burnham Aquastat

BurnhamBoiler

Hi, Trying to replace my Honeywell Aquastat # L4006A1009 on my 60 year old Burnham Holiday gas boiler model # 7-W-20, Series #2. Boiler is for hot water heat only.

The Honeywell Aquastat that is currently installed has a preset differential low temperature setting of only 5°. I believe this is causing my boiler to short cycle due to the 5° switching temperature difference

I would like to replace this Aquastat with a Honeywell model #L4006A1017.I would be using the old temp bulb well for the new one.

I understand that the L4006A1017 has an adjustable low temp differential as opposed to my old one & I'm hoping this will give a more reasonable 10° to 20° adjustment to cure my boiler short cycling.

Can you please tell me if the L4005A1017 would be a direct replacement for my old L4006A1009?

Would the original Aquastat have been correct in this boiler utilizing a fixed 5° differential?

Do you think the replacement will help with my boiler short cycling?

Thanks In Advance.

Steve

mattmia2

The old aquastat should have some markings on it telling you what the differential is. What makes you think it is short cycling? Have you checked the aquastat contacts with a voltmeter to confirm that the aquastat is what is opening to shut the burner off? Is this a 24vac system or a millivolt system or some other type of system?

BurnhamBoiler

Old Aquastat has no markings indicating the differential temperature. I looked up the Honeywell model# L4006A1009 specs & this is where I read the preset differential is only 5°.

System is a 24 vac.

When calling for heat, the Aquastat power on till my high setting of 185°. Once reached, it shuts off boiler till water temp lower to around 175/180° . Then Aquastat switches on again to open gas valve. Boiler only shuts off for approx 3 minutes then switches on for approximately 2 minutes to once again reach 185°.

This is why I believe this 5° differential Aquastat should have never been installed in the first place. Am I correct?

I would like boiler to run for longer periods with a larger temp differential to become more efficient. Am I correct?

Will the L4006A1017 be a compatibly replacement allowing me to adjust the lower differential temp?

Thanks again for any help!

Steve

Big Ed_4

Yes buy the adjustable diff model , it will just mount up to your system……

Make sure the bulb is inserted to the bottom of the ''well…

BurnhamBoiler

Excellent! Thanks Big Ed_4!!!!

mattmia2

is this a new problem or did it always do this? i'm thinking you may be trying to solve a circulation problem with an aquastat.

if you turn it down a bit it may still heat adequately but it won't lose heat as fast from the emitters so it might run a bit longer cycles. i wouldn't go below about 150 to prevent condensing.

EBEBRATT-Ed

Yes the new aqustat will fit in the existing well.

The ones with adjustable differential have a white wheel to adjust the diff. The ones with a fixed diff do not.

BurnhamBoiler

mattmia2. Yes. The boiler has always short cycled this way. I do have a thermometer on the return pipes & the difference is around 30° to 40°..The boiler keeps the house nice & warm & I only recently looked into the possible reasons why it may be short cycling. I was very surprised to find out that the Aquastat installed had a fixed differential of only 5°! Thanks for your help.

EBEBRATT-Ed. Thanks for second assuring me the L4006A1017. I believe this should do the trick to allow the boiler to cool just a bit more before refiring to solve the short cycling. I'll post back when I receive & install the new Aquastat.

mattmia2

if it is running a 30 degree delta t, does it have a bypass on the boiler? is it connected to a high mass system like a converted gravity system? it shouldn't be shutting off on high limit with a 30 degree delta t if the heat from the boiler is going out to the system.

BurnhamBoiler

No bypass & no gravity system. Maybe the boiler is a little oversized at 120,000 BTU for 1800 sqft home?

Boiler works great otherwise to warm house quickly, just concerned that short cycling of 5° diff Aquastat is not very efficient.

BurnhamBoiler

174024812887465123383249232344.jpg

Here's a pic of circulator/Aquastat

BurnhamBoiler

17402483063178762196337470644584.jpg

Front of boiler

EdTheHeaterMan

That Burnham is an oldie but goody. the B&G circulators are also great pumps. I can tell from the cover of your L4006A control that is probably the original. The replacement cover will have the cover screw on the top and/or bottom, not on the face of the cover. Getting an adjustable Diff. will make a difference. I would set it at 180° with a 25° Diff, and see how that works out for you.

And let me be the third to say, It will fit just fine. LOL

BurnhamBoiler

EdTheHeaterMan.... Thanks for another vote of confidence replacing the Aquastat.

The Burnham Holiday has been very dependable for the 30 years we have been in the house. The boiler is an original '65 unit which has only required the replacement of the auto water feed, leaky bleeder, pilot thermocouple & B &G #100's to b oiled seasonally. One is original '65 & the other is a replacement '79 pump.

I will never give up on this workhorse & have been collecting replacement parts just in case. I.E. replacement gas valve & rebuild kit for the B&G pumps.

Thanks for all the help & advice!!!