LWCO with water feeder question

Don_175

My mother has a gas fired steam boiler installed about 5 years ago. At Thanksgiving, I was looking at it and noticed the counter on her water feeder said 347 gallons. I asked about it, and she said that they had turned off the water not too long after installation as it was flooding boiler.

I looked at the dip switches and reset them so that there is a 2 minute delay before water is added, and it would only fill to LWCO. I watched the boiler while it was heating and water did not drop. The counter on feeder (which I had reset to 000), was still on 000 after a few days. All seemed well until last week when she said boiler has flooded twice. Counter is now reading 97 gallons.

She had a service person stop by, and he said both LWCO as well as feeder need to be replaced as they are "tied together". I'm thinking the probe is most likely the source of the problem and not the LWCO circuitry itself, and definitely not the water feeder as it is just responding to a call for water from the LWCO.

Is there anything I should be looking for? I hate to have her being taken advantage by someone. They are in southeast RI. For now, I had them manually turn off the water. Thanks.

Jamie Hall

Need to know both the make and model of the LWCO and the automatic feeder. There are several possible problems, most of which don't involve changing both...

Don_175

I'll have to doublecheck with her. I know the water feeder is a VXT with the red LED digits. I believe it is the 120 v unit. Not sure about LWCO

JUGHNE

That probe may not have been cleaned in 5 years.
It would be the first thing to check IMO.

neilc

if you post a couple pictures of the boiler, floor to ceiling, showing all the piping,
and a close up or 2 of the controls, sightglass, gage, and LWCO , , ,
we'll all have more to go on,

Gordo

She might need her VXT valve to be rebuilt. It is unlikely that the whole unit needs replacement.

The valve is the weak point of these autofeeders.

It also would be a good idea to "tighten up" the system...re-pack valves, replace questionable air vents, etc.

Hydrolevel's VXT re-build kit is #45-345 (on back-order, like everything else) and contains parts and instructions and is much less expensive than a new VXT.

Please check out the YouTube video on using the kit.

I have seen McDonnell Miller LWCOs intermittently send spurious signals to auto feeders even after the probe was cleaned, necessitating the whole replacement of said LWCO and probe.

EBEBRATT-Ed

@Don_175

I'll take a different approach. They have had this issue and obviously have been adding water to the system for about 5 years.

Do you really want to invest the $$ into this? How often do they have to add water manually in the past 5 years?

Problem is while @Gordo is the expert on these things her service company is going to throw the parts cannon at this and it will cost $$$$ when they get through.

Let's hear about the actual water usage first.

If feeding water manually is becoming difficult due to age or some other issue (like vacations) then the feeder is probably the best option

Don_175

That’s the thing…their system seems pretty tight. I noticed it was turned off, and she said they rarely have to manually add water. So the VXT was adding and flooding it. I told her to turn water off and keep an eye on the water level until I can get there and take a look. Thanks

Hap_Hazzard

Gordo said:

She might need her VXT valve to be rebuilt. It is unlikely that the whole unit needs replacement.

The valve is the weak point of these autofeeders.

But have you ever seen one fail open? It's been my understanding that diaphragm valves always get stuck shut when they fail, unlike a simple solenoid valve, which can go either way, but you've seen & worked on way more of these than I have.

Gordo

@Hap_Hazzard : I've seen them fail in both modes.

Of the two, the failure I've seen much more often is the failure for the valve (we are talking about the S-45 or the DEMA 443p) to cycle closed when the solenoid is de-energized. It will flood the steam system in short order.

Usually that seems to be caused by mineral build-up on the wettable internal surfaces. On the rubber diaphragm, there are two tiny holes that if they get clogged will clause it to fail open.

Just the other day, I ran into a VXT that failed to open and feed. It had been used a lot due to major leaks. The rubber had a layer of broken down mush. For me, that was a very rare failure.

Gordo

Here is a very long, boring discussion on the inner workings of the valves found on the VXT and such.
https://youtu.be/kUKby2WBYAU

Hap_Hazzard

Gordo said:

Just the other day, I ran into a VXT that failed to open and feed. It had been used a lot due to major leaks. The rubber had a layer of broken down mush. For me, that was a very rare failure.

This sounds like what I'd call the typical failure. I wonder if I've seen too few to have seen a representative sampling or if our local water conditions make the difference. ¯\_(ツ)_/¯

By the way, these valves (Dema 443P.3 and 443P.6) are used in some of those coin-operated car wash machines, so you can buy them from companies that sell replacement parts for that industry.
https://www.kleen-ritecorp.com/p-4427-dema-443p-3-nc-3-8-diaphragm-valve-with-epdm-seal-and-24-vac-spade-coil.aspx
https://www.kleen-ritecorp.com/p-4426-dema-443p-6-nc-3-8-diaphragm-valve-with-epdm-seal-and-120-vac-spade-coil.aspx
Compare their prices to SupplyHouse.com.
https://www.supplyhouse.com/Hydrolevel-45-343-Water-Feeder-Valve-Assembly-24V
https://www.supplyhouse.com/Hydrolevel-45-344-Water-Feeder-Valve-Assembly-120V
These do include the mounting bracket, but I don't think it's worth $55–85.

Paul Fredricks_3

I think the "97"on the VXT is minutes, not gallons. If the VXT was stuck open it wouldn't know how many gallons passed by it, just how long it was getting the call to feed.

Hap_Hazzard

Nope.

Paul Fredricks_3

The feeder records one gallon for every minute of operation, so you can read it either way. But it only records when it's being called for, so if it's stuck open that does not register on the counter.

EBEBRATT-Ed

@Gordo
I watch them all....not boring

Gordo

Hap_Hazzard said:

Gordo said:

Just the other day, I ran into a VXT that failed to open and feed. It had been used a lot due to major leaks. The rubber had a layer of broken down mush. For me, that was a very rare failure.

This sounds like what I'd call the typical failure. I wonder if I've seen too few to have seen a representative sampling or if our local water conditions make the difference. ¯\_(ツ)_/¯

By the way, these valves (Dema 443P.3 and 443P.6) are used in some of those coin-operated car wash machines, so you can buy them from companies that sell replacement parts for that industry.
https://www.kleen-ritecorp.com/p-4427-dema-443p-3-nc-3-8-diaphragm-valve-with-epdm-seal-and-24-vac-spade-coil.aspx
https://www.kleen-ritecorp.com/p-4426-dema-443p-6-nc-3-8-diaphragm-valve-with-epdm-seal-and-120-vac-spade-coil.aspx
Compare their prices to SupplyHouse.com.
https://www.supplyhouse.com/Hydrolevel-45-343-Water-Feeder-Valve-Assembly-24V
https://www.supplyhouse.com/Hydrolevel-45-344-Water-Feeder-Valve-Assembly-120V
These do include the mounting bracket, but I don't think it's worth $55–85.

We've seen the rubber break-down on some systems with well water. The most recent one for us was on City water (which in our area is pretty "good" as far as boilers -and apparently EPDM- are concerned).

As to the DEMA 443p valves sold by Kleen-Rite (excellent to deal with, BTW), they are missing the proper bracket for the VXT, as you correctly point out, and also the brass holder/adapter for the flow restricter and the flow restricter itself.
The bracket is VXT only and they can't sell it to us, and the other two items are special order.
And the solenoid does not come with the little bracket for screwing on, and so you might need a solenoid assembly. And none of the ones offered for sale through K-R are the "correct" orientation. Is that all worth the extra $55 to $85 ? Perhaps not.

ethicalpaul

That VXT must be pretty smart to know the water pressure at everyone's house. The gallon units is a complete estimate and not to be believed. It's good for counting how often there's a call for water of course which is all it needs to be.

Jamie Hall

Actually it could be remarkably close. I'm not sure it is, mind you, but it could be. There exist elastomeric valves which are designed to be constant (fixed) flow over a wide range of delta pressures. The ones I've seen for hydraulic systems are rather pricey -- but for water flow applications, looking at a tolerance of 10 percent, they're cheap.

JUGHNE

I have a VXT on my 1 pipe system of the "school hobby project" I have been working on.
I installed a standard water meter (checked with 5 gallon bucket fills) ahead of the VXT. The count numbers of the VXT matched the rotating gallon needle on the dial quite closely.
We have at best 35 PSI water pressure as the school in on "the hill".

Back when doing water to air heat pumps with the "Pump & Dump" method of ground water flow. We would install a flow restrictor for 3-4-6 gallons or whatever.
These had a rubber valve/orifice that would close down with higher pressure applied.
They were fed by a 30-50 PSI water pump. Worked well, never really measured the flow.

Hap_Hazzard

If I remember correctly, when the valve in my VXT got stuck closed, the counter stopped advancing, even when I pressed the feed button.