Water heater gremlins strike in the dead of night

[OurTown]

So if we wanted to get an aquastat that worked the same way but had a 3/8" diameter bulb then what would be suggested? I'm not coming up with much except maybe a Honeywell L6008G but I'm not sure it is the same type.

https://www.heritageparts.com/medias/CAP0182.pdf?context=bWFzdGVyfHBkZi1tYW51YWxzfDgwNTg4OHxhcHBsaWNhdGlvbi9wZGZ8cGRmLW1hbnVhbHMvaDRmL2hjZS84OTUxNDYzMjgwNjcwLnBkZnxkYzZlNWJkNTA4OGU0Yjc3MDdjODUzZDNkY2U3ZjE1M2QyYjMwZDM5YTIzZmNiMzY0ODZiOWIxYjNhY2Q0ZWM0

Can the remote bulb be replaced with the smaller diameter one? I couldn't find anything on that but that doesn't mean it can't be done.

 

[JGinther]

You can't swap sensing bulbs on any that I have ever seen. There's probably one out there that is what you need, but if you can't find it, why not just wire them so that you always have hi-fire? By your post, it appears that this is temporary anyway.

 

[OurTown]

You can't swap sensing bulbs on any that I have ever seen. There's probably one out there that is what you need, but if you can't find it, why not just wire them so that you always have hi-fire? By your post, it appears that this is temporary anyway.

I was able to easily unscrew the plate that the copper wire is soldered to on the back of the dial adjustment so if they make a different size remote bulb then it can obviously be swapped. The plan is for it to be temporary. If it is more efficient to run in low fire then why not wire it that way. I could always change it to high fire if it can't keep up.

 

[JGinther]

I'm pretty sure the bimetal spring portion is factory calibrated to the sensing bulb dynamics. Maybe not, but the last one I looked at appeared that way. It would probably still work, but the temperature setting wouldn't be accurate.

Since you are heating a water tank, it's not going to be effiecient anyway. You probably have a large btu and a relatively small reservoir. How long did the boiler run when nobody was using the wash? If you were heating a swimming pool, it would be a different story.

 

[OurTown]

I'm pretty sure the bimetal spring portion is factory calibrated to the sensing bulb dynamics. Maybe not, but the last one I looked at appeared that way. It would probably still work, but the temperature setting wouldn't be accurate.

Since you are heating a water tank, it's not going to be effiecient anyway. You probably have a large btu and a relatively small reservoir. How long did the boiler run when nobody was using the wash? If you were heating a swimming pool, it would be a different story.

I never really paid attention to how long the boiler ran but I will guess at 10 minutes. What type of aquastat should I be looking for? A "low limit" type?

 

[OurTown]

Also how much temperature differential do I need? Some are fixed at 5F and some are adjustable to higher temps.

 

[mjwalsh]

Also how much temperature differential do I need? Some are fixed at 5F and some are adjustable to higher temps.

OurTown,

Given a choice, I try to choose aquastats & thermostats with the ability to fine tune & adjust the differentials. Especially if the cost is not kicked up too much. I have had some thermistor based staging modules from Independent Energy out of Rhode Island that have been flawless since about 1990. One nice thing about thermistor based is that the sensor's &/or controller's accuracy can be somewhat verified use a multimeter on its ohm setting.

Observing how often whatever cycles is how I made the judgements & our subsequent adjustment for differential tweaks.

 

[OurTown]

I'm thinking that 5F is not enough differential because the boiler will kick on too often.

 

[OurTown]

Three aquastat questions remain:

1. How much temperature differential do I need?

2. Do I need a "break on rise" type?

3. If I bought a standard type (not one for a two stage) then would I combine the wiring so the low fire and high fire circuits would open and close at the same time?

On the internet I have not been able to find what we have but with the smaller 3/8" diameter bulb. I'm going to call the supplier that I bought the tank from to see what they recommend but wanted to be a little educated first.

 

[MEP001]

I've always used a 5 degree differential tankstat. I can't imagine why you'd want your water temp to vary 10 or more degrees. If you're heating water in a 60 gallon or larger tank the heater is going to run a few minutes to raise it back up 5 degrees, which I don't see as frequent starts.

The unit I've always used (Dayton) has both close on rise and open on rise. I would assume you'll need an open on rise if you use a SPST.

If you need to power both the low and high together, just wire them together. It's just sending power to the gas valve.

I think I have a Dayton switch somewhere - I'll pull the well off and measure the bulb. If you can find a 3/8" well that will accept the same size bulb, you could use a remote bulb unit and mount the controls somewhere.

 

[mjwalsh]

If you can find a 3/8" well that will accept the same size bulb, you could use a remote bulb unit and mount the controls somewhere.

Some HVAC control experts showed me after a major purchase from them gave me some heat sink compound so each thermistor with insulation over them ... could accomplish similar as putting in wells.

 

[MEP001]

Some HVAC control experts showed me after a major purchase from them gave me some heat sink compound so each thermistor with insulation over them ... could accomplish similar as putting in wells.

I've worked alongside enough "experts" in HVAC, electrical, and plumbing to know that most of them are idiots who prefer to take shortcuts that are illegal and dangerous for the sake of cutting costs or to get to the bar earlier. Have you ever seen a brand-new car wash wired with rusty, dirty, water-corroded components that were scrounged out of the back of a truck? I have. Have you ever seen a brand-new car wash where the electricians didn't want to get on the roof or spend money on extra strut so they mounted the Scottsdale lights to the underside of the roofing panel with toggle bolts, and the first time it rained there was water gushing out of the breaker box? I have.

 

[MEP001]

I just checked and was able to slide a 1/2" female to 3/8" male pipe thread adaptor over a thermostat well. It's a snug fit but there's plenty of material thickness that it could be sanded a 64th of an inch for a better fit if necessary. It will reduce how far the well fits into the tank but I feel it will penetrate enough to work properly.

 

[mjwalsh]

MEP001,

Well said ... I hear you loud, clear & can more than relate! This specific interaction took place at their shop when I picked up Trane Unit Heaters for our bays that the "experts" were also the local master distributor for (a friend-mechanical engineer tipped me off to them). Like the rest of us, they are not always wrong & this specific heatsink compound mounting with insulation over the copper pipe has proved to be a great alternative for us.

Annnuder ting ... I never was overly comfortable with the master-secondary exclusive monopoly like distributorships for some items in the HVAC ELECTRICAL fields. In other words: a sign shouting at you as you walk into the wholesalers': SALES TO LICENSED (contracting specialty) ONLY.

Happy New Year everyone!

 

[OurTown]

Annnuder ting ... I never was overly comfortable with the master-secondary exclusive monopoly like distributorships for some items in the HVAC ELECTRICAL fields. In other words: a sign shouting at you as you walk into the wholesalers': SALES TO LICENSED (contracting specialty) ONLY.

I run into that with HVAC the most and is hard to find one that will sell to the unlicensed. There is one plumbing supplier that is the same way but as far as electrical suppliers all the ones around here will sell to the unlicensed.

 

[OurTown]

I just checked and was able to slide a 1/2" female to 3/8" male pipe thread adaptor over a thermostat well. It's a snug fit but there's plenty of material thickness that it could be sanded a 64th of an inch for a better fit if necessary. It will reduce how far the well fits into the tank but I feel it will penetrate enough to work properly.

What we have on the new tank is what looks like a built in dry well that is 3/8" inside diameter by about 4 1/2" deep. There is so much insulation around it that I can't see if the well is screwed in or not. If it is and it is a 1/2" pipe thread then it could be replaced with a 1/2" ID copper well. (I have only seen these for sale in copper) The one in there looks to be stainless.

 

[MEP001]

I run into that with HVAC the most and is hard to find one that will sell to the unlicensed. There is one plumbing supplier that is the same way but as far as electrical suppliers all the ones around here will sell to the unlicensed.

It could be a case of the supplier not wanting to deal with sales tax. If they buy and sell only to those who are reselling, they can avoid all the hassles of retail sales.

 

[MEP001]

What we have on the new tank is what looks like a built in dry well that is 3/8" inside diameter by about 4 1/2" deep. There is so much insulation around it that I can't see if the well is screwed in or not. If it is and it is a 1/2" pipe thread then it could be replaced with a 1/2" ID copper well. (I have only seen these for sale in copper) The one in there looks to be stainless.

I see, so it's not a 3/8" pipe thread port for a well, it's a built-in well. If there's not a way to hang a thermostat from that, you'll have to use a remote bulb thermostat anyway. If the bulb doesn't fit the well with good contact inside, you can buy thermal transfer tape at computer electronics stores or online to wrap around the bulb.

 

[OurTown]

I'm having trouble finding an aquastat that will work okay. The only one that I can find is a Honeywell l4006a1959. Some of Honeywell's literature states is has a fixed differential of 5F, some say 2F, and some say either 2 or 5. Sellers are the same way. I ordered one from Grainger because they say theirs are 5 but it came in at 2. They thought that was strange so they brought one in from another warehouse and it came in at 2 also. I tried to order one from Boston Heating Supply because they state that it was 5 on their site. I ordered it but included a note for them to verify it was 5 before shipping it. They cancelled the order. I'm still looking for a 5 but in the meantime was wondering what differential everyone uses. To me the water temp is not as important as efficiency and boiler life. I'm guessing that a 2F diff would cycle the boiler more than twice as often. So the question is 2 deg too tight? Should I be looking at the electronic/digital type of controllers instead?

 

[MEP001]

Is the differential not adjustable? Grainger has a refrigerator version of that unit with an adjustable 5 to 20 degree differential.