Williamson Boiler HydroStat Temperature

Kennii

I recently got a new Williamson boiler with a tankless coil and the plumber set the HydroStat at 180. (I use the boiler for domestic hot water too) Today was really cold and I turned on the heat for the first time, but my baseboards wasn’t producing enough heat. I called the plumber and expressed my concerns, but he just said it’s a cold day and I’m using the boiler for the first time. All day, it was cold so I finally turned the HydroStat to 190 and the house got hot like it used to. I told the plumber and he said 190 is way too high and to put it back to 180 or I’ll have problems. 

My old boiler was a 1980’s peerless boiler that was on its last leg. Still worked—very noisy, but got the job done. 

Doing some research and I see that some plumbers don't like the HydroStat higher than 180 if domestic water shared with heat. 

Any input is appreciated.

EdTheHeaterMan

190° is fine if it gets the job done.

The low limit should be set near 160°.

There should also be a mixing valve on the DHW coil. It is in the instructions. 160°, 180°, 190° or even 200° is safe with the proper mixing valve.

With no mixing valve, even 140° is not safe. That first few cups of 140° water can scald you. It says so in the instructions at the top of page 13.

If this is the boiler I believe you purchased. It sounds like you may not have a mixing valve. You should call the installer and demand that the boiler be installed in accordance with the manufactures instructions.

If the installer did not leave the instructions, then here they are:https://www.williamson-thermoflo.com/sites/default/files/field-file/OWB OWT Boiler Manual - Series 3 1220_1.pdf

Kennii

Thank you for the reply. I did set the low at 160 and I have a mixing valve, but I have it closed.

EdTheHeaterMan

Kennii said:

Thank you for the reply. I did set the low at 160 and I have a mixing valve, but I have it closed.

Is your mixing valve the type that automatically adjusts the amount of cold water that needs to be added based on the water temperature of the hot that enters it?
Like these:
You don't want to close them. If you just have a regular valve and your plumber told you that it was the mixing valve, then he is incorrect.

Mr.Ed

PS
Could you post a picture of your mixing valve so we can see what you have.

EdTheHeaterMan

During normal operation of your oil burner, the water temperature that is in the boiler will go from 150° to 180° under normal operation. If you adjust it to 190° high limit then it will go from 150° to 190° under normal operation. When there is no call for heat, the 160° low limit will bring the burner on when ever the boiler water temperature drops below 150° the burner operates to bring the temperature back up to 160°. This is so there will always be enough heat in the boiler for domestic hot water to be adequate for showering and the like. No one wants a cold shower!

When there is a call for heat, the burner will start and the circulator pump will send that hot water to the radiators to heat the home. As long as the thermostat is calling for heat, the circulator will pump hot water into the radiators. If the burner keeps operating and all the heat is not used by the radiators, the boiler temperature will increase until it reaches the high limit temperature, then the burner stops, but the circulator keeps pumping the 190° to the radiators. The boiler temperature then slowly drops as the radiators give off the heat from that hot water circulating. When the boiler temperature drops by 10° to 180°, the burner will then start again. This cycling from the high limit will continue until the thermostat in the room is satisfied and both the burner and the circulator stop. This is all normal and the controls like the high limit and thermostat keeps you safe and comfortable that way.

Now let's imagine that we are water inside that coil for DHW. No one is using hot water and there is a call for heat. The boiler water all around us gets to be 190°. So of course we are in that DHW coil and absorb that heat as the water flows past us on the way to the radiators. We are now a nice toasty 190°. Now the 5 year old wants to help mommy and starts the bath water. First the water comes out cold (because the water sitting in the pipe is room temperature.). In about 8 to 15 seconds that 190° water reaches the tub and the child still has their hand in the water flow from the tub faucet. Then there is a loud scream and you are on your way to the emergency room.

Now if you had a mixing valve that is ASSE 1070 certified, or CSA Standard CAN/CSA B125-01, that would not happen. As the water leaving the coil goes thru the valve, there is a spring type thermostat (like the thermostat in some car radiators) that adjusts to add cold water to the hot water so the "Mix" water will always be the same temperature. This works great on tankless coil water heaters because the temperature coming out of that coils is constantly changing based on a call for heat or no call for heat and the like

I hope this explanation helps to get you where you need to be.

Mr. Ed

PS
Could you post a picture of your mixing valve so we can see what you have.

Kennii

Here is a picture of the mixing valve. It doesn’t look like the valves you showed.

also we set it back to 185 hi,

when both zones are on the temp will drop to 150’s or so and run for about 5-6 mins to get back to 190. 

We thought it was taking to long to get back to 190 hi, with both heating zones on.

if heat is not calling it will come on at 180 and run to 190, about 2 mins with pre and post purge included but get to hi teen temp 210-218. Usually stays above 180 for maybe 20-30 mins if no shower or heat on.

HVACNUT

I don't see how 10° makes a difference in early October. 180° should be more than enough. 
Is the economy setting used? With a tankless, it should be off.

Robert O'Brien

Kennii said:

Here is a picture of the mixing valve. It doesn’t look like the valves you showed.

also we set it back to 185 hi,

when both zones are on the temp will drop to 150’s or so and run for about 5-6 mins to get back to 190. 

We thought it was taking to long to get back to 190 hi, with both heating zones on.

if heat is not calling it will come on at 180 and run to 190, about 2 mins with pre and post purge included but get to hi teen temp 210-218. Usually stays above 180 for maybe 20-30 mins if no shower or heat on.

Long Island?

Kennii

HVACNUT said:

I don't see how 10° makes a difference in early October. 180° should be more than enough. 
Is the economy setting used? With a tankless, it should be off.

I don’t see an economy feature and I don’t think it has one. And yes, 10 degrees makes a difference when both zones are running. 

Kennii

Robert O'Brien said:

Kennii said:

Here is a picture of the mixing valve. It doesn’t look like the valves you showed.

also we set it back to 185 hi,

when both zones are on the temp will drop to 150’s or so and run for about 5-6 mins to get back to 190. 

We thought it was taking to long to get back to 190 hi, with both heating zones on.

if heat is not calling it will come on at 180 and run to 190, about 2 mins with pre and post purge included but get to hi teen temp 210-218. Usually stays above 180 for maybe 20-30 mins if no shower or heat on.

Long Island?

Yes, I’m in Long Island 

HVACNUT

Kennii said:

HVACNUT said:

I don't see how 10° makes a difference in early October. 180° should be more than enough. 
Is the economy setting used? With a tankless, it should be off.

I don’t see an economy feature and I don’t think it has one. And yes, 10 degrees makes a difference when both zones are running. 

What model Hydrostat? 3250 Plus? That model definitely has economy settings. 

Kennii

HVACNUT said:

Kennii said:

HVACNUT said:

I don't see how 10° makes a difference in early October. 180° should be more than enough. 
Is the economy setting used? With a tankless, it should be off.

I don’t see an economy feature and I don’t think it has one. And yes, 10 degrees makes a difference when both zones are running. 

What model Hydrostat? 3250 Plus? That model definitely has economy settings. 

It’s 3150

EdTheHeaterMan

WRONG VALVE FOR MIXING

That is known a a stop and waste valve. it is not an automatic mixing valve. A mixing valve will have 3 openings labeled H, C, and M.
H = Hot in
C = Cold in
M= Mixed out

Did you understand what I wrote in my comment about how your boiler and water heater operate?

You or someone you know may get scalded in the next 20 years or so if you don't install a proper mixing valve. If the original installer won't include it as shown in the manufacturer's instructions, then you should pay for it ASAP. If you don't do it, then at least increase your medical liability coverage on your homeowners insurance. That might be cheeper as long as you don't mind the insurance claim process.

If you plan it just right, your mother-in-law won't visit anymore after that.

Just say'n

DJD775

Kennii said:

Here is a picture of the mixing valve. It doesn’t look like the valves you showed.

also we set it back to 185 hi,

when both zones are on the temp will drop to 150’s or so and run for about 5-6 mins to get back to 190. 

We thought it was taking to long to get back to 190 hi, with both heating zones on.

if heat is not calling it will come on at 180 and run to 190, about 2 mins with pre and post purge included but get to hi teen temp 210-218. Usually stays above 180 for maybe 20-30 mins if no shower or heat on.

This doesn't make sense to me. If there is no call for heat you should be running between your low setting minus the low differential and your low setting, e.g. if your low setting is 160F and your low differential is 10F then you should be running between 150F-160F with no call for heat.

Also if only 190F water works at this time of year how is this system going to keep up in the middle of winter?
Might be time to contact a competent HVAC contractor to check your setup.

EdTheHeaterMan

There is an economy setting on the Hydrostat 3150

this may explain some of the temperature differences compared to the analog L8124 controls

DJD775

@EdTheHeaterMan
I don't think there thermal pre-purge should have much impact on the overall system effectiveness. It only holds off the burner on the first cycle and then after that it returns to normal triple aquastat operation.

EdTheHeaterMan

@Kennii, You mention "Both Zones" in your reply. That means 2 thermostats. What are the other ends of the thermostat wires connected to, Zone Valves or to a pump relay? or something else? A picture of the 2 zone valves, or the 2 pumps or the zone control panel. There are so many ways to correctly wire your system. And there are so many ways to make mistakes in wiring your system.

A picture from far enough back to see the piping near the boiler from floor to ceiling would also help.

HVACNUT

Ok, the 3150 must come as a package on boilers with a tankless coil. 

When you say, "but my baseboards wasn't producing enough heat." What was the temperature in the house? What temperature did you set the thermostat? How long did you wait for it to reach the set temperature? Again, unless there's a lot of air in the pipes, or poor pumping, baseboard dirty or blocked, 180° in early October at the North pole would be sufficient. 

EdTheHeaterMan

After looking at what you sent me on PM, you have 2 circulator pumps. There may be a necessary control missing. The plumber should have used one of these
or at least one of these.
and included 2 new thermostats.
You did not see anything like either of those controls on the wall near your new heater, Did You?

I believe the second circulator zone is operated by a line voltage thermostat, since there is no circulator control for your other zone. Not the most efficient design. Your new boiler is using more oil than necessary with your present wiring and control settings.

Put that husband of yours on here and I'll let him know how concerned you are about this, and rightly so!