descaling 3 way thermostatic mix valves? try this method

hot_rod

We get these valves returned, and most of the time the valves are seized up. It's very rare to find a factory defect in the valve. Inside it is a fairly simple mechanism, spool, spring, o-rings and thermostatic "pill"

Recently we have been discouraging disassembly to clean the valve onsite. The potential to damage the o-rings or spool, lose parts, or reassemble incorrectly is high, especially without a exploded view drawing. Repair techs sometimes dis-assemble them not realizing there is a spring inside and the parts go flying

So I though about using one of the tankless heater de-scaling kits. This is the Haymaker (odd name) unless you live in Missouri farm country, as I do, from Hercules™.

I drilled a few holes in the lid with a holesaw, a Unibit would work also. Get a spare lid to reseal the bucket for the next job.

I use one of the washer Y-hoses found at most plumbing or hardware stores, connect to H&C ports and onto pump with hose supplied in the kit.

A couple 3/4 mip tailpieces, which may be on the valve if you have a threaded version. Flatten the end with a file or belt sander so the hose washer seal tightly.

Assemble the valve to the lid, use a nut to lock it to the lid, connect the small submersible pump, included in the Haymaker, add the "juice" and run for 20- 30 minutes. I used 1/2 the dilution rate noted on the bucket, and it was plenty powerful.

Run time might depend on how badly the valve is scaled. We have had some returned where the ports were completely sealed off with scale or lime build up. Turn the knob a few times as the cleaner runs.

Here is a before and after look of the valves.

If you have a Caleffi Pump Cart, the lid already has a garden hose adapter, you just need a hose coupler and a Y hose.

Now if you install 3 way valves with a Webstone type ball/purge valve on all ports the valve could be de-limed in place, like you would a tankless heater.

Thoughts? donations? royalties?

BobC

Looks like good old Yankee ingenuity to me!

Bob

RobG

If you were doing it for your own home I can see it being cost effective, but if your on a service call I would just replace it as the time is the main cost factor. JMHO

hot_rod

RobG said:

If you were doing it for your own home I can see it being cost effective, but if your on a service call I would just replace it as the time is the main cost factor. JMHO

True enough, but gather enough of the removed ones, take them to the shop and bring them back to life with this cleaning.

No reason to discard a valve that just needs a cleaning.

These were valves that had been replaced already and I didn't want to scrap out.

RobG

hot rod said:

RobG said:

If you were doing it for your own home I can see it being cost effective, but if your on a service call I would just replace it as the time is the main cost factor. JMHO

True enough, but gather enough of the removed ones, take them to the shop and bring them back to life with this cleaning.

No reason to discard a valve that just needs a cleaning.

These were valves that had been replaced already and I didn't want to scrap out.

If you had the time would just leaving it soaking in the de-scaler for a longer period of time and then just agitating the unit to shake loose the debris work? If that would work then you just keep two on hand and swap out as necessary No need for the pump assembly?.

hot_rod

we have some customers that d-scale valves every 3 months! A simple pump connection could be as fast as a switch out, still a 1 hour service call.

On the larger sizes, 1-1/4 and above $$, you would not want to switch in an out and keep spares in inventory. Unless the building owner wanted to pay for a back up valve in your inventory.

Just offering options, we sell thousands of these valves and always look for maintenance options.

RobG

hot rod said:

we have some customers that d-scale valves every 3 months! A simple pump connection could be as fast as a switch out, still a 1 hour service call.

On the larger sizes, 1-1/4 and above $$, you would not want to switch in an out and keep spares in inventory. Unless the building owner wanted to pay for a back up valve in your inventory.

Just offering options, we sell thousands of these valves and always look for maintenance options.

Interesting, but would just soaking for a longer amount of time and manual agitation work?

hot_rod

RobG said:

hot rod said:

we have some customers that d-scale valves every 3 months! A simple pump connection could be as fast as a switch out, still a 1 hour service call.

On the larger sizes, 1-1/4 and above $$, you would not want to switch in an out and keep spares in inventory. Unless the building owner wanted to pay for a back up valve in your inventory.

Just offering options, we sell thousands of these valves and always look for maintenance options.

Interesting, but would just soaking for a longer amount of time and manual agitation work?

I think you would need to disassemble the valve if you were going to drop it in a bucket and "shake and bake"

Ever seen the parts cleaners they use in auto shops? They are an open tank, but have an air hose connection to agitate the fluid.

With the tight passage ways in thermostatic valves, I figured a pressurized flow through all those openings, around the o rings would be the best way to a thorough cleaning.

Mainly trying to eliminate the dis-assembly of the valve.

Actually, we now glue that top, plastic, indicator ring onto the plastic body to prevent dis-assembly.

We do test every single valve with H&C connected to them at the factory.

If you or someone else dis-assembles the valve, the liability and certification is now in question. It's a very strict ASSE standard, any mis-assembly errors can compromise the whole product performance. Remember this is a critical safety device, many a lawsuit revolve around temperature safety devices.

If you talk with anyone that has been named in a "soft tissue" lawsuit, it's not a pleasant experience.

hot_rod

Hatterasguy said:

Speaking of descaling and slightly OT, what are you currently using on your FPHX for hot water? You've had that for quite a few years now.

Very curious as to your experience with it and how often it needs your attention and what the preferred chemical and procedure is?

I would assume you do something very similar as the three way valve above?

I have a few systems running here at my place. The shop has a 3X8 40 plate, 9 square feet of hx maybe, on the side of an HTP Solar Phoenix. That has been plenty for a hand sink and shower use. I can run the tank as low as 115F and still get a hot shower. It has been on several years I have not de-scaled it yet. It does have softened water running to it.

The house has a 5X10 30 plate on the side of a 50 gallon buffer tank, that has been on a year or so, softened water also. I run that tank at 140F for the dry, plate radiant it supplies.

I also have a 120 Lochinvar Cadet with the DHW plate HX function. It has a small HX, too small, and not enough hp from a 120,000. If it can receive solar pre-heat it keeps up, not so well in winter months however. I think you really need 150K or more to do a good job of instant DHW via a HX, for a family.

My mother in law has a 130 Laars Mascot boiler/ DHW and it servers her well, been running 6 years now, I have not flushed it yet, softened water down there also. It does have a solar pre-heat also.

I like the Webstone, or other brand of these three port valves, for plate HX service. It's very simple to connect a de-scale pump as needed.

I've used Hercules Sizzle for years to de-scale boilers and HXers. I'm not sure what acid comes in those tankless flush kits? It doesn't seem as strong as the Sizzle.

Or connect the HX with 4 unions so it can be removed. One customer removes his every 2 years and takes it to a radiator shop to cook it out. It provides a small radiant loop from his DHW tank, no water softener on that system.

This HX cut a way was on a solar system on an apartment bldg for 20 years! I doubt it was ever flushed. This fed 3- 120 gallon tanks, so quick recovery was not an issue.

3 main factors for DHW HXers

How hot the water is heated going into the HX
How hard the water is
How many gallons they run through it.

DHW via a HX is a favorite topic, we have talked about it is 3 or 4 Ironic issues, this for #6

The software programs are the easiest way to "look" at HX performance, here is some math for pencil pushers.