EFM 350

"Switched the wires on the switching relay" how?

Let's break this down into bite-sized chunks... all this testing can be done at the boiler, no stairs required. If you're running up and down stairs to turn on a thermostat, there are a few hacks to do this at the taco: bring a thermostat down to the taco and wire it in; use a small piece of wire to double-tap the terminals; pull the thermostat wires out a little to expose bare copper and use an alligator test lead to short them out. You'll need two screwdrivers and voltmeter for this.

We're going to test 5 things:
aquastat temp and burner controls
aquastat ZC power output
taco ZR power output
aquastat ZR power input
taco ZC power input

First, before we start testing, let's prepare the taco. disconnect the ZC and ZR wires from the taco (turn off power when connecting or disconnecting these since they're 120V wires). Also, remove any of the ZC-ZR or X-ZC jumpers. Nothing in X-X-ZC-ZR.

Now, the aquastat. first, make a note of the HI LO DIFF settings. do you have T-T or C1-C2 connected on your aquastat? if you're running all the zones off the taco, you shouldn't - because these will run independently of the ZC-ZR logic. if you had, this could be the whole problem. The aquastat should now have just L1-L2, B1-B2 connected - we're just first testing the burner circuit.

If your DIFF isn't 10, let's set it to 10 for this experiment - just makes it easier to follow. now, based on whatever the temp of the water in the boiler is, let's rotate the LO and HI dials. If the boiler is running, rotate the LO lower until you hit the (boiler temp - 10*) and it should shut off at that point. If the boiler is off, rotate the LO higher and the burner should come on when you go past the boiler temp. rotate the HI lower and the burner should shut off when you get to the boiler temp. rotate the HI back up and after 10* of movement, the boiler should fire back on. Take the HI back to the original setting. Now, rotate the LO back down to the original setting - if it was off to start, it should go off, if it was on, it should stay on until the temp is reached. Reset your DIFF if you changed it. This will verify the aquastat is powering the burner circuit correctly.

Remember that ZC sends power from the aquastat to the taco. ZC is on the hot side, so, on the the aquastat, measure voltage between ZC and L2. Whenever LO is satisfied, ZC should have 120V; so if the boiler is off, it should be 120V, if running, it should be 0V. Rotate the LO dial to check each state. You can check ZR voltage and it should be 0V in both states, since the taco is disconnected. If this checks out, ZC is working on the aquastat, so let's move over to the taco.

Let's continue to leave the ZC and ZR disconnected on the taco. ZR is the opposite flow from ZC: from the taco to the aquastat. So, with no zones calling for heat, measuring voltage between ZR and N should be 0V. Now, turn on a zone and ZR should have 120V. If this checks out, ZR is working on the taco. ZC will have 0V in both states since it's disconnected from the aquastat.

Now, let's connect only ZR back up on the taco (power off to make the connection). Measure voltage on ZR and N. It should be the same as you just did before: no call for heat = 0V, calling for heat = 120V. BUT... since we have ZR wired to the aquastat, if we call for heat, the boiler should start up - unless you're at HI limit, so if it doesn't adjust your HI up and try again. If this checks out, then we have proved that ZR works on both controls. If you changed your HI, move it back to your original setting. Only one more thing...

Let's hook ZC back up (power off, as above). Now, we should be at our desired wiring state: aquastat has L1 and L2, B1 and B2, and now ZC and ZR; taco has ZC and ZR wired, nothing in the X-X, no X-ZC jumper, no ZC-ZR jumper. Double-double check that ZC goes to ZC and ZR goes to ZR. triple double check with your multimeter if the leads are long enough: disconnect one of them at both ends and check continuity (continuity check won't work if either end is connected).

Now, the circulators shouldn't run if the temp is below LO. To test it, call for heat and the boiler should start up (unless HI, as above). If boiler temp is at or above LO, the circulator should run. If boiler temp is below LO, the circulator shouldn't run. You can rotate the LO to emulate each state. If this checks out, then we have proved that ZC works on both controls and the problem is not with the aquastat or the taco.

A reminder to reset your aquastat's settings if you changed them during testing.

If something doesn't work, pics of your setup will help.

have not had time to mess with the wiring, got busy out in the shop, couple friends vehicles are falling apart as usual, and the rest of my time is taking care of the meals and housework.

since it's been warmer i have used very little coal. around 20 pounds a day.
the pex got quieter when i replaced the mounting clips. the larger expansion tank is working well.

the heat exchanger zone has not called in days, the kitchen is 74 degrees and the thermostat is set for 71.

the cast iron radiator zone will call like once or twice a day and i have that thermostat set at 73. the boiler is heating the house without the need for circulation lol.
this may be a problem when it gets hot outside. i'm going to have to replace the central air.

would insulating the primary loop help any? or should i get some fans for the basement windows?

i have the garage set at 60 and most days it's a few degrees warmer out there if the sun is shining in the windows.

really loving this efm 350!

the power went out yesterday for 5 hours and we did not lose the fire. Also the primary loop circulates by gravity without the circulator pump power. The inch and a quarter loop was equally hot from the top of the boiler to the return.
This means I can shut the primary loop pump off in the summer?

without going to look at photos, do you have a flow preventer on your primary line? it's like a backflow preventer but in reverse. and if so, is it installed correctly? they have an arrow on them showing the flow direction. if you don't do this, gravity will circulate the water and heat the house all year and you'll burn a few extra tons of coal over the summer until you look at the preventers and scream at the guy who installed them backwards. or, at least, that's what I hear happens... If you want to keep gravity circulation for power outages in the winter, at least put a ball valve on it so you can stop it circulating all summer long.

is the primary loop a heating loop? if so, insulating it will help in the summer and hurt in the winter (when it's free radiation). Decide which is more important for you. But if it's too hot due to gravity-induced circulation, take care of that first.

LouSee wrote: ↑

Mon. Apr. 12, 2021 8:40 pm

without going to look at photos, do you have a flow preventer on your primary line? it's like a backflow preventer but in reverse. and if so, is it installed correctly? they have an arrow on them showing the flow direction. if you don't do this, gravity will circulate the water and heat the house all year and you'll burn a few extra tons of coal over the summer until you look at the preventers and scream at the guy who installed them backwards. or, at least, that's what I hear happens... If you want to keep gravity circulation for power outages in the winter, at least put a ball valve on it so you can stop it circulating all summer long.

is the primary loop a heating loop? if so, insulating it will help in the summer and hurt in the winter (when it's free radiation). Decide which is more important for you. But if it's too hot due to gravity-induced circulation, take care of that first.

There is no ifc on the primary loop pump. it came with the pump but it was damaged. read a whole lot about the subject and never saw a reference to a ifc so i left it out.
The boiler does not use much coal when it's warm. 15-20 pounds a day.
I have ball valves on the primary loop. Two for the circulator and one to isolate the boiler from the air scoop. If I close one of those there is no boiler bypass though.
here are some pics of the primary loop and the valves.

LouSee wrote: ↑

Mon. Apr. 12, 2021 8:40 pm

without going to look at photos, do you have a flow preventer on your primary line? it's like a backflow preventer but in reverse. and if so, is it installed correctly? they have an arrow on them showing the flow direction. if you don't do this, gravity will circulate the water and heat the house all year and you'll burn a few extra tons of coal over the summer until you look at the preventers and scream at the guy who installed them backwards. or, at least, that's what I hear happens... If you want to keep gravity circulation for power outages in the winter, at least put a ball valve on it so you can stop it circulating all summer long.

is the primary loop a heating loop? if so, insulating it will help in the summer and hurt in the winter (when it's free radiation). Decide which is more important for you. But if it's too hot due to gravity-induced circulation, take care of that first.

I live between two creeks in a valley, we have a damp basement issue so i was hoping this boiler would also act as a dehumidifier. it's just a bit warm in the house lol. Wish my dad was here to see what i got done down there, he tried for years to keep the water from coming in. in 1971 he had a new slab poured, that's when he found out the house has no footers. the slab is 6" thick and acts as the footer now. in 1972 hurricane agnes came in 1972 and the water came thru the walls ever since, he tried to stop the flow but he couldn't. the oil furnace and the well pump and the washing machine got flooded more times than i can count when i was a kid. at one point my dad was considering moving the house and putting in a new basement but he could not find a excavator and mason that would work under the house. it was 3 bucks a square foot in 1980 to jack up the house and put it on new foundation. fast forward and we have sewer now and the water table dropped from a few inches below the ground to about 4 feet. I have two sump pumps installed and the one runs every few minutes and the other one runs when it rains heavy.
one zone on the primary hot loop is for a future basement radiator (once i get the radiators installed in the addition the heat exchanger is coming out of the furnace and that zone will be for a cast iron radiator, the big ugly green one.

guess i'll have to experiment with shutting off the primary pump and closing the valve or insulate.
i can't find foam insulation for the 1.25" pipe, all i see is fiberglass at lowes and home depot. do the supply houses have the larger sizes in foam?

Rob R. wrote: ↑

Tue. Apr. 13, 2021 10:43 am

Do you have flow checks in the secondary circuits?

Yes, the secondary circulators have ifc's

thanks rob, that was my next question when seeing the new circulators. 15 pounds a day doesn't feel like much for hot water but then, I have no idea how much I burn since I don't weigh it. I just know I go 3-4 days to a bucket change in the summer - depending on the wife's showers, of course.

if you're going to do a basement radiator, i'd insulate. having the bypass loop is more important. i don't know about 1.25" foam, but you can use 2 pieces - 1 each for 1/2" & 3/4" - and get coverage for the pipe that way.

I got new central a/c going in may 30th so decision i need to make is to finish the 2 zones in the back of the house or move the furnace down off of one of the two sets of blocks it sits on and raise the plenum to keep the water to air heat exchanger. i would have to order two small radiators from pexuniverse. they are 120 each shipped.

Could move HX to the return air side then no blocks to change.

We got the a/c coil in there without moving the furnace.

Went to check on the efm this afternoon and the fire was out.
cleaned up the mess and re lit the stoker.
not sure how well that timer works. i don't think it comes on twice an hour like it should. anyone have an instruction manual for the timer?

You should be able to find one online, no?

fire is out again. timer does not work. must have been the aquastat keeping the boiler lit. i turned off the primary loop and blocked one of the zones off because the check valve was letting hot water by to the heat exchanger. those were the only changes i made.