How to adjust this aquastat

[BillTheEngineer]

It is a high limit aquastat, per the manual, but I guess it's also a low limit or differential for when to kick back on when there is a call for heat.

Original manual lists it as a Raypak 601013 - adj auto high limit
looks like it's replaced by: Raypak 014307F

 

[Heyjoe]

It is a high limit aquastat, per the manual, but I guess it's also a low limit or differential for when to kick back on when there is a call for heat.

Original manual lists it as a Raypak 601013 - adj auto high limit
looks like it's replaced by: Raypak 014307F

View attachment 59691

First off I am no plumber. My high limit looks something like yours. Your photo looks like yours is set at 160 degrees. On mind I manually turn the wheel to the water temperature I want. The directions say there is a small hole, paper clip size that will let me change the factory stop, Its not in the way so I have never done that and mind is set to fire after a 5 degree change. On the left side of mine there is another wheel that sets the differential.
I am glad you posted this because I always thought the 5 degrees was to high, but factory fixed.I watched a video on YouTube by PexUniverse and it said to set the differential at 20???

 

[Sponsor]

 

[Fitter30]

Being a limit thats what the factory wants it at the controls differential is also factory set. Why do you want to change the setting? It's not the temp control.
https://www.supplyhouse.com/Raypak-014307F-Temperature-Controller#product-overview

 

[BillTheEngineer]

It's an older gas boiler (late 80's Raypak H3-135B), it's was beginning to make so noise from boiling when it was approached the high limit shut off. I took apart the boiler yesterday and cleaned the outside of the heat exchanger (there was a fair bit of debris in it that has made it's way down the chimney). Cleaning it did help but it was still making noise from 190°F to 195°F (after cleaning). Before started at 180°F- 185°F.

I figured turning the dial would change the high cut off limit. Is the arm on the dial to set the differential? would moving that either way change the differential?

I would have cleaned the inside of the heat exchanger but didn't have new seals for putting it back together. And i can live with some noise and heat, as opposed to no noise and no heat.

It's a 2 stage boiler (yes it's way oversize) and I have already disabled the 2nd stage so it runs about at half (~60 kbtu based on the manual, not sure if that is input or output), but it can keep up on the coldest days. With both stages going it would make a lot more noise. The second stage has been disabled for a few years.

It may also be one of the circulators is getting weak and not flowing as much as it should.

 

[Fitter30]

Only thing I've found on your boiler is a parts list and exploded view. See it has a copper fin tube heat exchanger. What type of noise is it making? Popping and cracking maybe a sizzle.Has this boiler seen alot of makep water in 30+ years if so the exchanger is limed up and i wouldn't touch it 30 years old. Time for a change before it starts leaking.
copper tubes have fins external and the interal has like fine screw threads called enhanced.

 

[BillTheEngineer]

I don't know how much make up water it has gone through. In the past 6 or 7 years I have only flushed it once when I changed the fill valve, relief valve and air vent. All were done at the same time. I didn't see signs of leakage between the tubes and headers or anywhere else. There is one circulator flange that looks like crap but it's was that way when I bought the house.

The noise it was making was a low pitch whistling. I could hear it throughout the house and at the boiler. It would only happen for 10 to 20 seconds and stop once the boiler reached the high limit and shut off (circulator still running). I can't say for sure but didn't seem to matter how many times were calling for heat. Difficult to turn them on or off when it was whistling, since it didn't last to long.

I am aware it doesn't owe me anything, but my heating bills are low and it's been working. It's only used for space heating. DHW is stand alone and well past it due date too. Ideally I'll replace them when it's warm when heat and hot water aren't necessary.