Thermostat off for spring, DHW is lukewarm now - Honeywell L4006A on 2-pipe steam w/ DHW coil

seandempsey

I turned my thermostat to "off" for spring and am letting the heat pumps take over, giving the 2-pipe steam radiators their summer break. I have a 2-pipe steam system and a DHW coil that does my hot water.

However, once I turned the thermostat to "off" 2 days ago, which caused my boiler to not heat the radiators to steam temperatures to get the house to 66F (which was about 2 hours of boiler time each day), my showers are far too cold, almost lukewarm.

Now, I know enough to check the aquastate, but mine doesn't have the differentia wheel as I see when I google the model 4006A. As you can see in the photos I just took, I turned the wheel to 185F to try and keep the DHW temp higher, but it didn't seem to work.

One factor to note: I need basically infinite hot water for showers because I have a mentally disabled adult child who uses hot showers as a form of regulation and decompression. So this is not a financial concern, the infininte hot water is effectively a medical necessity (and a topic for another day).

So here's my big question: how do I make it so the showers are hot again? Heating the boiler water to steam heat for running the radiators kept it nice and toasty, but now just 2 days in, the aquatstat is not keeping it much more than just warm.

I tried looking up the model, and the manual I found for this aquastate has a wheel where you can clearly see a spot for one on my photo, but it's not there. And turning it to 185F yesterday didn't make today's water any hotter.

I also took a picture of the mixer that comes out of the coil, but I have no experience with those and would love some advice. I hestiate to adjust ot turn anything as it is so old and my experience level is still growing, if it leaks or breaks, I'll be back to calling around for emergency service.

What is my next step here? I don't know why my aquastat doesn't have a differential wheel or low/high setting and just the single dial on the front. What can I do right now today to get the water hot again, other than artificially making the thermostat turn on/off via the Nest control to let it just try and heat for an hour twice a day, which is what I presume the aquastat is supposed to do.

And just to be certain - the thermostat has been off for 2 days and the water is still coming out warm, so the boiler is warming up throughout the day as needed, just not enough.

Oh also - the water level on the (new) sign glass shows that the water level is up to the top of the coil assembly, which is where my techinician told me to keep it so the DHW coil is completely in the hot boiler water.

I feel like there's some information I don't know about, so if this is a clear solve, please let me know what to do next! Thanks as always!

EDIT: I see this page in the manual shows that it "breaks" the connection at the limit and can either be wired for high or low limit - by turning it up a bit to 185F, did I actually go the wrong direction? And how would I determine if my aquastat is setup to break the connection on high or low?

ethicalpaul

If you're going to DIY this (it's good to have a heating technician you trust to keep this system working), you have to see if the aquastat is making the connection between its two contacts as you'd expect, and you also have to check the wiring of the aquastat to ensure that it is going to activate your boiler.

The second part is very easy, you can jump across the aquastat temporarily and under supervision with a wire to see if that fires up your boiler.

If that works you will know your aquastat isn't doing its job and you can explore that further.

PS: things are looking pretty crusty over there

seandempsey

I believe the aquastat is working, I can hear the boiler turn on throughout the day yesterday and today, and with the thermostat off there are no other devices that would turn on the burner other than the aquastat.

And yes, it's very crusty down there. I am renovating this old system and house as money allows :D

ethicalpaul

OK then I guess it's just a question of if it's working as you want it to. I think an aquastat expert will answer better, but there are ways to make sure it is really "seeing" the actual temperature of the water vs being insulated from that.

Have you observed it during a long period of hot water usage to see when it comes on and turns off? that might give you some clues. Do you have a way of measuring the temperature of the water in the boiler?

seandempsey

https://forum.heatinghelp.com/discussion/comment/1744207#Comment_1744207

I don't have a way to determine the boiler's temp, but that's a good idea. I will look to see if I can Google how I can get some realtime monitoring.

The world of 20th century boilers and smart homes needs to meet 🤣 I would love WiFi enabled devices on all of this.

ethicalpaul

I put a water boiler-style temp gauge on my steam boiler when I added my water loop. It would be hard to add for ol' Rusty there 😅

EdTheHeaterMan

How high is the water in the boiler? Some of those coils are 1/2 in the water and 1/2 in the steam. You may get better performance if you add water to raise the water level to the top of the sight glass. Leave about 1/2" of air space at the top of the gauge glass.

HVACNUT

The mixing valve says CCW for warmer. Have you tried turning it?

What is the aquastat wired to?

It would be nice to have a steam pro go over the whole system

EdTheHeaterMan

Since Steamers do not come with water temperature gauges, you will need to get a thermometer that can strap on the Hot Out pipe of the coil. There are some inexpensive thermometers that can do that. Once the thermometer is in place and no hot water has been used for at least 20 minutes, Turn on the Hot water on slow, and watch the thermometer. Tt should give you a good idea of the boiler temperature for the first 20 seconds. That will also be the boiler water temperature. After that, the temperature will drop as the colder water reaches the OUT end of the coil. Now you will be reading the "temperature rise" water temperature which will be lower based on the amount of build up there is inside and outside the tankless coil.

My guess is there is not been any maintenance on that coil for years. Could probably use a good flush with some tankless water heater cleaner.

Larry Weingarten

Hi, I'd also alook at the mixing valve. I've had a lot of trouble over the years with that one scaling up and not closing fully… that is always mixing cold water in, even when not needed. I'd feel the cold supply to that valve and see if it gets cold what trying to run hot water.

Yours, Larry