Automatic Water Feeder shuts off power at low water? Plumber says it's the thermostat

lowwater

Here's the situation. Hope you can help me. I have a:

-Honeywell YTHX9421R5010 Prestige IAQ Comfort System Kit (Includes Thermostat, EIM, Portable Comfort Control, Outdoor Sensor)

- Burnham SIN5LNC gas steam boiler

- McDonnell low water cut off 24 v.a.c switch PSE-802



We have a manual water feeder before, and everything was working fine. Note that when the boiler ran out of hot water, the water cut off switch would cut off power to the thermostat (not sure if that's normal, but it's part of the problem below).



Our plumber installed a VXT-24 automatic water feeder switch. The problem is that when the boiler runs out of water, the power gets cut off, including to the VXT which is connected to the McDonell, so the boiler doesn't get refilled.



Our plumber is convinced the Honeywell is the root cause of the problems (he hasn't seen this type of thermostat before), but I'm not so sure. Why can't the VXT get it's power from the transformer directly, instead of getting it from the McDonell cut off switch? Does it makes sense the thermostat gets it power cut off when the boiler runs out of water?



Right now we're at a standstill since the plumber doesn't want to deal with it until we install a normal thermostat.



FYI - EIM connectors used: R,C to thermostat, W1, R, C to boiler.



PSE-802 to VXT: N (white), H (Red).



Edit: I have done some more research. Shouldn't there be a 3rd, feed, cable from the PSE-802 to the VXT?



Manuals:

<a href="http://ecomfort.com/PDF_files/Hydrolevel/hydrolevel_vxt-24_install_instructions.pdf">http://ecomfort.com/PDF_files/Hydrolevel/hydrolevel_vxt-24_install_instructions.pdf</a>

<a href="http://s3.pexsupply.com/product_files/Mcdonnell%20&%20Miller%20-%20153602-LWCO%20-%20Install%20Instructions.pdf">http://s3.pexsupply.com/product_files/Mcdonnell%20&%20Miller%20-%20153602-LWCO%20-%20Install%20Instructions.pdf</a>



Thank you,

Mark

Zman

T-stat

The t-stat should be hooked to the isolated thermostat relay.

The Low water cut off should be wired in series with the other safety switches.

They should not impact each other.

Beyond that, the fill valve should be tied to the LWCO per the manual and everything should be fine.

Carl

lowwater

?

Carl... In my plain, non plumber English are you saying that the

thermostat cannot affect the feeder? Is it normal that the thermostat

get's shut off when when the unit runs out of water? How does the wiring

look to you (see above)? Thanks!

Zman

T-stat

I am assuming that this is the correct manual for your boiler http://cdn.usboiler.net/products/boilers/independence/assets/Independence.pdf



If so the t-stat should always be powered regardless of the LWCO. The boiler will not fire if the LWCO is open.



Can you take pictures and make a drawing of your setup?



It sounds like the LWCO it powering off everything and as you said causing the auto fill to not work.



Yes there should be 3 wires.

It looks like the feeder should be wired like the drawing labled

PS-800 Series

STANDARD WIRING – NEWER MODELS

It is hard to tell because the manufacture assumes no one knows how to read schematics so they don't print them.



Carl

Steamhead

The Burnham Independence boilers

have a relay which the thermostat operates to energize the 24V circuit that operates the gas valve. it should not affect the LWCO or water feeder. I think someone has some wires crossed.

Jamie Hall

There is no way

that thing is wired correctly.  Nor is there any way that the problem is the thermostat; plumbers are not always the best electricians (I would note that electricians are frequently lousy plumbers; it goes both ways).



A thermostat is a switch which responds to temperature -- that's true whether it's a T87 or a Nest or anything in between.



Get the wiring straightened out.  Shouldn't be that hard...

lowwater

Connectivity

All I appreciate the feedback and help! Here's some information:



Manuals:

water feeder: http://ecomfort.com/PDF_files/Hydrolevel/hydrolevel_vxt-24_install_instructions.pdf

cut off: http://s3.pexsupply.com/product_files/Mcdonnell%20&%20Miller%20-%20153602-LWCO%20-%20Install%20Instructions.pdf

boiler: http://cdn.usboiler.net/products/boilers/independence/assets/Independence.pdf

thermostat: http://s3.pexsupply.com/manuals/1281719057640/36393_PROD_FILE.pdf



Wires:

water feeder to cut off: N (white), H [jumper to C] (Red).



24vac transformer:

Yellow to C EIN, Boiler

Blue -> Boiler

White -> Boiler

Black -> Boiler

Boiler white -> W1 EIN

Boiler Red -> R EIN

The thermostat is powered from the EIN



Note: the EIN is the thermostat control unit

Zman

One line?

Any chance you could do a simple one line drawing? Just a simple hand drawn showing the devices and how they are connected would be fine. At first glance it looks like you are short a common somewhere. It makes my head hurt without a drawing.

Carl

icesailor

Basic Boiler Control Wiring:

The "Plumber" doesn't understand basic boiler control wiring.

If he doesn't understand how it works, he needs to stop futzing and trying to DX control wiring because he clearly doesn't know the rats front from the back.

You need someone else that knows how it is supposed to work. The thermostat is nor normally wired into the safety control circuit. I say it that way because there may be some circumstance that I am not aware of. The Thermostat tells the burner to start. The safety control circuits must all be closed for the burner to start. The "Plumber" should be able to show you how the thermostat is causing the problem. Not just make some empirical statement that through FM, the burner won't start. It's something else. Experience will lead the way. The "Plumber" needs more experience.

lowwater

Wiring

Thanks all for the help. Please note that I'm not a professional (neither plumber nor electrician), so bear with me



Uploaded is the diagram to the very best of my knowledge. I am not sure if it's 100% correct or labeled correctly, but it looks about right. The most tricky part is the splicer (also found in the pictures). I also noticed that the orange cable has a grey jumper cables.



So the question is: why does the when the water cut off gets triggered, all the power to both the water feeder and EIN/thermostat also gets cut off?

Zman

Drawing?

It looks like your thermostat is connected to the boiler incorrectly. Are there terminals on the boiler that are not being used? Perhaps labeled "TT"  or "R1 W1" ?  You also seem to have some incorrect wiringl between the LWCO and the feeder.

The problem is once you find something wired this far off, who knows what else they screwed up. I think you should use this info to help find a professional who is qualified to fix it. Once someone has reconfigured the safety circuit, you need to be positive it is fixed correctly. There is a potential that the boiler could fire with a closed damper or that another safety has been inadvertently bypassed.

I think it is time to get someone to look at it that understands controls.

Carl

lowwater

Clarification

I appreciate all the help. Let me try to describe the items:

- Splicer: a plastic electricity splicer where a bunch of cable come in one side, and go out another

- PSI box: I believe this is called a Honeywell pressuretrol

- Boiler valve: cables that are running down and inside the boiler. I believe this is might lead to the ignition system (I mistakenly called it a valve). Hope this helps.

lowwater

Carl

Carl... Who would be most qualified to look into this? Apparently not a plumber? An electrician? Do they know boilers?

Zman

In a nutshell...

The t-stat should be connected to the boiler's isolated t-stat relay. Yours looks like it is wired into the boilers safety circuit.



When the LWCO detects low water it should disable the boiler's ability to fire (the t-stats should be unaffected). It should then signal the water feeder to add water. Once the water is at  the correct level, the lwco should read this and the  boiler should fire.By your drawing it looks like this is wired incorrectly.



My concern about trying to diagnose and repair this via the internet is that your boiler has been visited by at least one knucklehead. Knuckleheads don't know much about controls. They will just keep moving wires around until it works. By "works" I mean the boiler will get hot and you will stop calling them to fix it.



Any good heating company should have folks that understand how these systems work. They should be able to make sure the boiler is wired according to the diagram in the manual and that it is safe to operate. I know some great electricians and have yet to find one that wants to look at boiler controls. Go figure.



Carl

lowwater

Thank you

Thank you all for responding. Much appreciated. 

Charlie from wmass

Where is the boiler?

There are several contractors in the find a contractor section above that can find the issue and fix it .

Jamie Hall

I do hope,

lowwater, that you have gathered at least one thing from this thread:  your controls are completely mis-wired.  I really can't answer your particular question -- why does the power shut off at low water? -- from looking at your diagram (but thank you for the diagram!), as some of the internals are not completely clear.



However, that doesn't stop me from saying -- quite firmly -- that I don't think, from the look of it, that there is one single correct circuit in the whole thing except for the two wires from the thermostat to the thermostat EIN.  Those are probably right...



I would suggest that you rip out all the wiring (except those two wires) and start all over again with the parts manuals to hand.  If you are good at electricity, you might be able to do this yourself.  Otherwise, do yourself a favour and take Charles' suggestion: find a good steam boiler man in your area and let him straighten it out.



It isn't rocket science, but it does have to be done properly.