Honeywell triple aquastat L8124G

dermottusmc

Ok here is my question, I bought this home with the on demand water heater coil not in use, do I need a different aquastat? Can I just change the setting?

EBEBRATT-Ed

You have an aquastat control that has a low limit setting used to operate the burner to maintain hot water temp for your tankless heater. Since you no longer use the tankless the boiler is still maintaining water temp. The low limit part of the control cannot be disabled.

You have 3 choices #1 is the cheapest followed by #2 & #3

#1 Shut the power off and remove the cover. Set the "low limit" down as low as it will go. The burner will still operate occasionally to maintain a low water temp. Turn the power back on

#2 Buy a switching relay such as a Honeywell RA89A (there may be a newer model #). Taco, Argo and others make an equal relay.
Remove the thermostat wires from the aqustat. Install a jumper in place of the thermostat wires. Connect the thermostat wire to T & T on the new relay. Bring 120v power to the new relay and wire the contacts in series with the 120 volt power to the old aqustat relay.
#3 Remove and replace the aquastat with a new model like a "hydrostat" #3150

You could do #2 but it's a little bit of work. The new aquastat is probably less labor but more $ in parts cost

dermottusmc

Thank you so much!

dermottusmc

I will go with a new one, I jumped the W & the R (to by pass low limit) to see if that would work, now it just stays at the high limit set temp. There is no diagram for the differential dial so not sure where to set it now. In the grand scheme of my plan is I am going to install the tekmar 402 with the t stats and outside reset switch.

STEVEusaPA

There is a #4...

But you should just replace it with the hydrostat and new well, then you'll get LWCO, and circulator hold off, both very important.
You may not want ODR with oil, probably will cause short cycling. You'll also need to protect for cold water/low temp water returning into the boiler.

leonz

You should do number 1 and leave it as is for your system.
I have an L8124L1011 for my boiler and it has been trouble free. My last set of honeywell mechanical controls worked 28 years without fail.
The new hydrostat 3250 plus I was given failed as did the replacement unit and that is why I went back to the honeywell mechanical L8124L1011 as it is simple and is a proven design that works and works well.

dermottusmc

Is there a mechanical hydrostat? It (tekmar House Control 402) appears to control every thing, so I don't think I need a electronic one. I didn't include that I also ordered the 3 way valve and the actuating Motor for boiler protection. I have a WTGO Oil Boiler weil mclain
Thank you all for your help, retired Vet here, just bought my first home. After 27 years of combine service, I finally settle down in one place. My back ground is that I am also a retired commercial electrician.

STEVEusaPA

Option 1 is a good idea if the H/O turns off the system in the spring. But you will burn oil to maintain temperature. There's nothing wrong with a Hydrostat. Like I said, take advantage of the LWCO and boiler protection.

leonz

Hello SteveusaPA,

I cautioned him to not purchase a hydrostat 3250 plus and leave his current honeywell unit in place because I had two bad units the first one failed to stop a near boil out and the second one had a mind of its own and turned the low water cut off function off as I was standing there watching the unit work while I was running it on oil to test it.

To DermottUSMC,

You can safely leave the current honeywell triple aquastat it in place.
A mechanical triple aquastat is a very reliable boiler control system and is not affected by voltage spikes or brown outs that would ruin a hydrostat digital triple aquastat.

The other thing is the The hydrostats do not come with the onductive paste that would normally be packed in with a mechanical triple aquastat.

With the highly conductive paste you cut one corner of the package and push the paste into the thermocouple well and then slide the thermocouple into the well all the way until it stops and no further.

HVACNUT

I dont think I've ever had a problem with the 3250 Plus when set correctly and no tephlon tape.

STEVEusaPA

HVACNUT said:

I dont think I've ever had a problem with the 3250 Plus when set correctly and no tephlon tape.

Same here.

leonz said:

Hello SteveusaPA,

I cautioned him to not purchase a hydrostat 3250 plus and leave his current honeywell unit in place because I had two bad units the first one failed to stop a near boil out and the second one had a mind of its own and turned the low water cut off function off as I was standing there watching the unit work while I was running it on oil to test it.

Us regulars are well aware of your experiences with this aquastat, your enthusiasm for your coal stoker, and your love of steel expansion tanks. Your are entitled to your opinion, but you should tell people your only experience is with your own equipment so readers can give it the proper weight it deserves.
Things you recommend are just not the proper advice, antiquated, or just plain wrong.

To the OP, I'm sorry to tell you this, but you're wasting your money on the Tekmar. With oil, the outdoor reset on that boiler is pretty worthless. 80% of the winter you're going to be targeting 140 degrees, short cycling most of the winter, except on the coldest days of winter.
Unfortunately, despite being an electrician, you cut the wrong wire, and you should replace the aquastat.

Once again, install the Hydrolevel 3250plus with the new well, take advantage of the LWCO, pre-purge, economy mode, circulator hold off, etc, etc. You can even add outdoor reset.

leonz

SO I guess your saying the steel compression tank was a poorly designed antiquated way to provide low system pressure in hydronic system by the deadmen with the actual ballast weight of the water aiding in heating a home or business of any size when they were first developed and used in Basements or in the attic of a gravity hot water heating system was wrong and is wrong? There are more than a handful of gravity hot water systems still operating to this day with open to air expansion tanks.

I wanted simple basic plumbing with no frills like an air scoop or automatic air vents that I would have to change every time they started leaking.

My living without running for months because of a well failure caused many heating issues with pressure loss due to a bad automatic fill valve and no back flow preventer in 1981 that allowed the system pressure to drop and th eheating system to become useless and as result we had not heat The added expense of having a plumbers helper come up with a jet pump and getting water from a neighbor to push water back into the system is no picnic and it cost a lot of money back then.

It may be an older way of doing things but they work and even the open to air steel expansion tank I had hanging in my ceiling was just as effective for heating and worked well with the single loop heating system that was installed in this house in 1953 and we always had heat with no leaks.

As far as my experience with the hydrostat 3250 plus goes I guess had the same failures that 56 other keystoker boiler owners had when they had their coal stoker boilers installed by licensed plumbers in Pennsylvania.

People tend to forget that the simpler a heating system is the less troublesome it is.


I will no longer comment on this thread, thank you.

dermottusmc

Actually I didn't cut the wire I disconnected it, the wire diagram shows I by passed the low temp limit contact that is all it did. I will find out on this set up this winter, right now I pay an average of 400 a month for fuel so this is a option I will try.

dermottusmc

This tekmar system components was an anonymous housewarming gift, the gift card said "thank you for your service"!