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Tankless Coil Aquastat Settings?

I have a Peerless WBV-03 single pipe steam boiler with a tankless coil and I just want to make sure the aquastat for the DHW is set appropriately. Its a Honeywell L4006 that only has Hi and Diff adjustments. Does that mean Lo is automatically Hi minus Diff? Currently, Hi is 180 and Diff is 10, but my research shows Diff should be more like 20, but wanted to double check.
EDIT: Changed L6006 to L4006
EDIT: Changed L6006 to L4006
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Comments
Is 180 setpoint with 20 Diff a typical default setting? I am still not clear on how the diff works.
EDIT: Oops, I had the wrong model number before. Its actually an L4006A with setpoint and diff. Does this change anything?
When you adjust the differential to 20° the new high limit is 190°. 10° more than the setpoint of 180°. The contacts close when the temperature drops below 170° and the contacts open when the water temperature rises above 190°. It is just a switch that turns on and off based on the temperature you select and the differential; you select.
Regarding the water pressure, you should have a mixing valve on the system. That mixing valve may be partially restricted. A good cleaning of the mixing valve and the tankless coil will bring the system back to optimum performance.
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
If the differential is set at 10° then the 180° setting was actually 175° cut in and 185° cut off.
Set the differential at the maximum of 30° and the 180° setpoint and the high cut-off would be 195° and the low cut-in temperature would be 165°. This would also need to be verified by actual testing after installing the control.
The actual reading on the thermostats, controls, and thermometers have liberal tolerance. Testing is the fail-safe of the installing technician. Just installing the part without verification is not good practice.
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
Bburd
Somewhat related question - the water pressure entering our house is ~80 psi which I understand to be a bit high but not crazy. Is it worth installing a pressure reducing valve at this pressure? And if I do, do I need an expansion tank for my coil?
A pressure reducing valve PRV set at say 50 PSI would be a good idea for all the valves and fixtures on the system. less stress on the moving parts... "Yada... Yada... Yada..."
If you have a PRV you should install a small expansion tank for the same reasons as the PRV (all those Yadas above). As the cold water from underground piping enters the home and warms up to room temperature, it will expand and increase pressure if there is no place to go. You see the PRV acts like a check valve and will not allow the expanding water to flow back into the water company piping system (backward thru the meter.) Your water meter may also have a backflow preventer connected for that same reason.
Also, the water in the tankless coil will expand once the hot water valve, tap, or washing machine solenoid valve closes. Since there is no "top of the water heater air cushion" to accept this expansion, and in many cases, there are no relief valves on tankless coils (I could never figure out why that was not enforced) the pressure exerted on many faucets and valves can be tremendous. But it goes away as soon as someone opens a valve (like the ice maker on your refrigerator).
Regarding the tankless coil cleaning, There are 3 that I have used successfully. All three require that you have isolation valves on the hot and cold water side of the coil and a boiler drain valve on either side of the coil between the iso valves and the coil. This way you can flush the mess out of the pipe without putting any of the debris into the rest of the hot water system throughout the house... clogging up all the little strainers.
After the valves are in place you can try the first one. It is free.
1 Shock the crap off
A. First, you need the get a garden hose about 3 to 5 ft long (Washing Machine connector works well)
B. You also need a 5-gallon pail.
C. Connect the hose to the boiler drain of the hot outlet of the coil.
D. Set all thermostats in the home to off or the lowest temperature. No calls for heat. and record where the aquastat settings are.
E. Set the boiler high limit to 235°
F. Set the low limit to 225° Turn on the switch to operate the burner.
G. Once the boiler temperature is at 225° let the water in the tankless coil absorbed the heat for a minute or so.
H. Place the free end of the garden hose in the 5-gallon pail. You may want to have something to clamp the end of the hose so it stays in the bucket.
I. Close the cold water inlet to the tankless coil and then open the boiler drain on the hot discharge. The water pressure in the coil will drop to atmospheric pressure and the water in the coil will flash to steam shocking off a significant amount of crud and crap.
J. within a few seconds, after the pressure is released, open the cold water supply to the coil and shock the coil again with cold water against the hot copper inside the boiler.
K. close the boiler drain to the 5-gallon pail after the water runs clear.
L. Empty the bucket and let the boiler heat the water in the coil for about 10 minutes.
M. Repeat steps H thru L for a total of 3 flushes.
2 Acid the crrap off
A. Shut off the hot and cold water valves to the coil
B. Open the boiler drains
C. Connect hoses to the boiler drain valves and place one in the 5-gallon pail.
D. Using a hand pump or standpipe apply 1 part Hercules Sizzleand 2 parts water into the coil until it runs out the other side drain valve.
E. Let it sit until foaming stops.
F. Add more sizzle as needed.
G. Adding more sizzle with no foaming means the coil is clean.
H. Flush the coil with cold water of all the chemicals and run water out the hot water drain for 5 minutes after the chemical has cleared.
I. Use the enclosed test to be sure the water is at the proper pH before opening the hot water isolation valve.
J. Flush all the hot water faucets for about 2-3 minute each, to be sure all the chemical is gone from the system before drinking, cooking or showering.
Caution this acid may cause the copper pipe to fail if the corrosion is extensive. You may need to replace the coil after procedure #1 or #2 ...but that would happen soon anyway without cleaning.
3 Maintain the crap off
Use vinegar-based cleaner or tankless coil cleaner on a regular basis (annually or bi-annually) depending on your water condition. Here is a good kit to use.
Do NOT use this setup with Hercules Sizzle.
https://www.homedepot.com/p/Flush-Kit-for-Tankless-Water-Heaters-RTG20124/202798886?source=shoppingads&locale=en-US&mtc=Shopping-VF-F_D26P-G-D26P-26_10_WATER_HEATERS-MULTI-NA-Feed-PLA-NA-NA-WATER_HEATERS&cm_mmc=Shopping-VF-F_D26P-G-D26P-26_10_WATER_HEATERS-MULTI-NA-Feed-PLA-NA-NA-WATER_HEATERS-71700000033150351-58700003868932468-92700049176334365&gclid=Cj0KCQiA0fr_BRDaARIsAABw4EsPV0QrLRg3tH2mAAVNnek6EmkJyLi7ijANsrQOy1AHT4Bi7RsOujIaAvjIEALw_wcB&gclsrc=aw.ds
Yours Truly,
Mr.Ed
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
Would I need an actual expansion tank or would a large water hammer arrestor like Watts 150A suffice? Also, where on the system would the expansion tank go? I know my mixing valve has check valves on both the hot and cold inlets.
"Would I need an actual expansion tank or would a large water hammer arrestor like Watts 150A suffice? Also, where on the system would the expansion tank go? I know my mixing valve has check valves on both the hot and cold inlets."
As far as cleaning, think I'll probably wait until summer when I won't need the boiler for heat since I'll need to add valves to connect the hoses to the coil etc.
That is what happens when you just copy and paste without reading the information.
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
A. First, you need the get a garden hose about 3 to 5 ft long (Washing Machine connector works well)
B. You also need a 5-gallon pail.
C. Connect the hose to the boiler drain of the hot outlet of the coil.
D.
Set all thermostats in the home to off or the lowest temperature. No calls for heat. and record where the aquastat settings are.Turn on the switch to operate the burner. and jump out the thermostat or turn it up to 90°E. Set the boiler high limit to 235°
F. Set the low limit to 225°
G. Once the boiler
temperature is at 225° begins to make steam, let the water in the tankless coil absorbed the heat for a minute or so.H. Place the free end of the garden hose in the 5-gallon pail. You may want to have something to clamp the end of the hose so it stays in the bucket.
I. Close the cold water inlet to the tankless coil and then open the boiler drain on the hot discharge. The water pressure in the coil will drop to atmospheric pressure and the water in the coil will flash to steam shocking off a significant amount of crud and crap.
J. within a few seconds, after the pressure is released, open the cold water supply to the coil and shock the coil again with cold water against the hot copper inside the boiler.
K. close the boiler drain to the 5-gallon pail after the water runs clear.
L. Empty the bucket and let the boiler heat the water in the coil for about 10 minutes.
M. Repeat steps H thru L for a total of 3 flushes.
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
Still looking for an answer to these questions if you don't mind. This is in reference to me adding a PRV on the system.
You also need to provide for expansion anywhere there is a valve that prevents the release of pressure in reverse to any other expansion allowance device, meaning you may need more than one if there are multiple check valves and backflow preventers. This is where you have to think like water in your mind's eye and say "If I were water where would I go if heated?" If there is no place then you need to make a place.
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?
@hot_rod or @Youngplumber should be able to verify the potable water expansion tank location. I'm an oil heat and Hydronics guy.
Respectfully submitted,
Mr.Ed
Retired HVAC Contractor from So. Jersey Shore.
Cleaned & services first oil heating system at age 16
Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
If you make an expensive repair and the same problem happens, What will you check next?