Steam boiler not sending power to thermostat

Tom106

Hello, any help here would be appreciated. My steam boiler stopped sending power to my Nest Thermostat. I noticed the boiler was repeatedly filling up which makes me think the LWCO is faulty? So far I have fully drained the system and refilled (it was clogged with black sludge), I have taken off the LWCO and cleaned the probe. The LWCO is working enough to know when the water is below the probe and touching the probe. What would be the next step here? It’s Sunday and trying to hold off on calling a pro until tomorrow but am also a fairly handy person and would like to tackle this myself if possible. Thanks. 

GW

When you say steam boiler and nest in the same sentence, more questions get asked. Most steam boilers don’t have a traditional 24 V output (no C or common connection). I had to learn this the hard way several years ago.

 How many wires is your nest running on? This is the age old question with the Nast. They really do need a traditional 24 V power source.When we do a nest/Ecobee on a steamer, we set up a separate transformer, and a relay. This might be what you’re facing.

Also, many heating/HVAC guys despise Nast and Ecobee. I’m not in that category yet. They seem to be working out when we touch and feel them. Just have to know the nuances.

GW

Stupid iPhone, voice to text.

Tom106

GW said:

When you say steam boiler and nest in the same sentence, more questions get asked. Most steam boilers don’t have a traditional 24 V output (no C or common connection). I had to learn this the hard way several years ago.

 How many wires is your nest running on? This is the age old question with the Nast. They really do need a traditional 24 V power source.When we do a nest/Ecobee on a steamer, we set up a separate transformer, and a relay. This might be what you’re facing.

Also, many heating/HVAC guys despise Nast and Ecobee. I’m not in that category yet. They seem to be working out when we touch and feel them. Just have to know the nuances.

The Nest is running off the red and white wire (no AC). The Nest worked fine for a week after install but this just started yesterday. I am seeing a tag on my wires that connect the boiler wiring to the thermostat wiring that says “TO 24V THERMOSTAT”

Jamie Hall

It is sometimes possible to persuade a Nest to run off just two wires. Sometimes. Unlikely, however, if you have an otherwise normal steam boiler.

The tag on the wires at the boiler is a little misleading. What it means is that you are to connect a thermostat rated for 24 VAC operation -- not that those two wires carry 24 VAC power. In fact, they may carry no power at all, since what the boiler is looking for on those wires is not power, but just a closed circuit.

That the Nest worked find for a week just tells you it took that long for its backup battery to discharge.

You will need a separate 24VAC power supply for the Nest. You can get that from a transformer in the basement plus a relay as @GW says, or I believe that there are wall warts which can be used to power the Nest.

STEVEusaPA

GW said:

Stupid iPhone, voice to text.

"Nast" sounds about right.

GW

Hence- The mystery of the nest. The mystery is, sometimes they work on two wires, other times they do not.

Seems like your nest ran out of juice. You can take it off the wall and plug it in to the USB charger. 

Tom106

Jamie Hall said:

It is sometimes possible to persuade a Nest to run off just two wires. Sometimes. Unlikely, however, if you have an otherwise normal steam boiler. The tag on the wires at the boiler is a little misleading. What it means is that you are to connect a thermostat rated for 24 VAC operation -- not that those two wires carry 24 VAC power. In fact, they may carry no power at all, since what the boiler is looking for on those wires is not power, but just a closed circuit. That the Nest worked find for a week just tells you it took that long for its backup battery to discharge. You will need a separate 24VAC power supply for the Nest. You can get that from a transformer in the basement plus a relay as @GW says, or I believe that there are wall warts which can be used to power the Nest.

Appreciate the input here. Would it be possible that since the Nest isn’t cooperating that this would make the boiler have the water auto fill kick on repeatedly for the boiler? 

I noticed the water kicking on constantly once this started. I attempted to drain and it was clogged so I flushed the system. Had to use a coat hanger to unclog the drain and a bunch of black sludge came out. 

neilc

if you pull the nest off the base,
do you still have the water filling problem ?
or do you loose all power to the boiler / water filler?

Tom106

The power remains on. Basically in my uneducated opinion I’m guessing the LWCO is old and misfiring and sending a signal to the auto fill to keep filling and in turn is telling the boiler to not run. Is this possible? I cleaned the probe and it does light up red when the water is low. The LWCO equipment looks older than the auto fill equipment (I purchased this house in July so not fully familiar with the dates on all the parts). 

Also I attached the old thermostat that was working for years and it does not appear to have changed the boiler not running issue. 

neilc

the water thing,
or you could be leaking, bad.
any wet returns that are under the slab?
or other water on the floor we should know about?

if you turn the boiler off all together at the service switch,
does the water level drop in say an hour (or 2s) ?

Tom106

There are no signs of leaking water. No water on ground. The auto fill is running a five cycle fill and then stopping after the five cycles. When I turn off the power it resets the auto fill and does another five cycles. I can turn it off for a couple hours and monitor the level on the gauge. 

Jamie Hall

You have two possibly quite unrelated problems here. Powering the Nest and your autofill not operating properly. Which are we trying to solve?

pecmsg

STEVEusaPA said:

Stupid iPhone, voice to text.

"Nast" sounds about right.

Nasty describes NEST better. 

Tom106

Jamie Hall said:

You have two possibly quite unrelated problems here. Powering the Nest and your autofill not operating properly. Which are we trying to solve?

To be honest I was never concerned with the nest lol. I am concerned with the auto feed water problem. I turned off the boiler for a couple hours and water level has not budged. It is confirmed it is not leaking. Something is telling the auto feed to feed water. My guess is still an old outdated LWCO but I am not super knowledgeable  on this. 

Tom106

Left is auto feed. Middle is LWCO. Right is water gauge, which the water is near that rusty spot on the top. 

Jamie Hall

It may be time to replace the LWCO...

Tom106

Thanks Jamie! And thanks everyone for responding to this. I will have to call around some local spots in Cleveland, OH tomorrow to try and find a replacement piece for the LWCO. I’ll let y’all know if this works. 

Tom106

New LWCO fixed the problem! Boiler is fired up, Nest is receiving power from the boiler (once the house warms up I’ll test to see if the nest is truly getting that 24V), and the auto fill is not auto filling anymore (once it hits the probe level). Thanks again to all who responded!