Bad zone valve or aquastat

Avasonsyn

Hello Everyone
I can only get hot water if I jump the aquastat at the water tank. I replaced the zone valve because when I manually pushed the lever, my furnace kicked on (could have been by chance...I don't know). Also, the zone valve that I purchased had an open box so I'm thinking maybe the valve was used and not good. The only time I can get the furnace to kick on and get hot water, is if I jump the aquastat. As soon as I take the jumper off, The furnace kicks off. I have an L4006 honeywell aquastat. Thanks in advance!

John Ruhnke

By jumping out the aquastat and it fires the boiler you are proving that the rest of the system works. You have isolated the problem. Now you need to look at the final three possibilities. The aquastat itself, its sensor or its well.

Avasonsyn

Thanks for the quick reply! I should probably just replace the aquastat correct? I don’t know squat about the sensor. Thanks again! That was FAST!

John Ruhnke

The sensor and the aquastat are sold together. In order to change the well you need to drain the heater. You could buy a well and first try things without the well. Most likely the well is fine. They make a heat transfer jell that comes with the aquastat. Just squirt it in the well before sticking in the sensor.

Avasonsyn

Great! I think I will return the zone valve that I just put in. The box was already open and I will tell them that. Put the old one in and buy an aquastat. Jeez! Those things are pricey. I will be sure to post after I replace aquastat. Thank you!!

Avasonsyn

One more thing...is it dangerous to leave that jumper in for the night until I can get an aquastat?

Jamie Hall

Yes. It's supposed to shut off the system at a set high temperature. With the jumper in there, it won't -- and the best result will be water all over the floor when the temperature and pressure relief valve opens. If it opens... if not... well... not good.

Avasonsyn

That is great advice. I will just jump it tonight when hot showers are in order. I will get a new part tomorrow and go from there. Again, I will let everyone know the outcome. I returned the old/new zone valve today and asked the person not to put it back on the shelf because it did look used when I bought it. Thanks again HVACRs!

HVACNUT

There are other numbers after L4006A that are important. Make sure you get the same or comparable. Things like well (bottom or back mount) or surface mount, temperature and differential settings.

Avasonsyn

Picked up a new aquastat at the plumbing store today. Replaced it. After running the hot water for about 5 minutes, the furnace kicked on. I was happy. My furnace is set at 180 degrees and its taking some time to get to that temperature. It's probably been about 20 minutes or so. Any idea where to set the aquastat temperature and the the temperature differential setting? Should I set it at 10-15 degrees? Again...Thank you everyone!

Avasonsyn

Furnace just turned off...I hate to get ahead of myself but it looks like things are in order. This is what the internet was supposed to be about. I will update in a few days. Thank you everyone! I'm sure I will post more questions about my outdoor woodburner in the next few weeks or so.

Avasonsyn

I’ve searched this and other forums. It seems there is no definitive answer out there. I’m going to contact Honeywell and see if I can get a straight answer.

John Ruhnke

@Avasonsyn

According to the codes for dhw you should set the aquastat to 120 degrees. 20 degrees is a standard differential setting. To prevent legionaries disease the water needs to be set higher than 135 degrees. To compensate for the hotter water you should have a mixing valve installed on the hot water outlet leaving the heater to mix it down to 120 degrees.

Avasonsyn

That's sounds great. I appreciate the time everyone puts in to help out. I will make the changes.

Avasonsyn

Hey guys...everything has been great up to last night. No hot water. Jumped the aquastat and furnace fired up. Any thoughts or suggestions? I’m going to the plumbing place to ask them to test the stat. I’m not sure if that’s even possible but I’ll ask any way. Any help would be appreciated. Thanks!

HVACNUT

Jumping out the aquastat and making the burner fire doesn't necessarily mean the aquastat is the culprit.
The indirect circulator was definitely NOT running when you first noticed no hot water?
Was the boiler cold?
Did you install another L4006A?
Wire connections are good on the screw terminals?
You made sure the aquastat capillary is seated all the way to the back of the well?
Reading back it looks like temp is set to 120° and a 20° diff? As said, the tank should be kept at about 145°, 10° diff, and a thermostatic mixing valve set to 120° out to the house.
Ever read Plum Island?

Avasonsyn

So did you what you suggested. It seemed as if the wires were tight. Took them off and snugged them. Going on day two. Seems to be working well. Thank you! I've never read Plum Island before. Should I?