dirt separators with Lochinvar buffer tanks

roundrightfarm

I'm installing a Lochinvar mod-con system with their 30 gallon Squire buffer tank and am wondering about the need of a dirt separator and its placement. The buffer tank will be configured as a 4 pipe system.

I read this in an online article-
"The low flow velocities (in buffer tanks) allow dirt particles that may be present in the flow returning from the distribution system to drop to the bottom of the tank. The only problem is most buffer tanks are not designed to efficiently flush out dirt that settles to the bottom of the tank. Dirt that happens to settle near the drain valve may get entrained with flow out the bottom tank drain, but the low local flow velocities in other lower areas of the tank cannot effectively entrain dirt and, thus, are unable to carry it to the drain connection. As such, most buffer tanks can eventually separate and accumulate dirt, but are not good at ridding the system of that dirt. This is why a modern dirt separator, which can generate sufficient internal flow velocity during a flush to entrain any accumulated dirt, is the preferred choice.

Does anyone know the shape of the innards of a Lochinvar Squire buffer tank? Are they designed to collect dirt to be removed by the drain? Or should I add a dirt separator? If so, where is the best place to put it in relation to the buffer tank and expansion tank and fill valve?

kcopp

What is the system like? Lot of steel? Cast iron? Old system? New?

roundrightfarm

new mod con system, Lochinvar WHN111, with indirect water heater and a Grundfos Alpha distribution circulator for heating a microzoned TRV system.

hot_rod

As Kevin inquired, any old piping, radiators steel pipe? If not you may not see much dirt accumulation. Most tanks have domed ends, usually domed up into the tank, so debris would collect around that "head" A bottom drain cock would flush most out.

With an ECM circulator I'd like to see a mag separator of some sort, however. Typical low velocity zone or vortex separators greatly benefit from a magnetic function.

roundrightfarm

Thanks for the feedback. This will be a new pex installation, no older pipes.

Would the best spot for a magnetic dirt separator be on the return line between the boiler pump and boiler, or between buffer tank and the boiler pump, or between the buffer tank and distribution return piping? or elsewhere?

kcopp

What is your radiation? Fin tube? Panels rads? Radiant? If it a radiant floor set up I would say don't bother w/ the magnetic separator... Clean (water side) of the system at commissioning time and use good fill water. A good inhibitor to the system wouldn't hurt.

Rich_49

Between the boiler circ and the buffer . The buffer will take some of the garbage and the separator will get more .

hot_rod

You will want a good micro bubble type of air separator in the system. Install it at the hottest point, right out of the boiler supply.

The domed top of buffer tanks is a good place to collect air bubbles, but it will not scrub out the micro bubbles that form when water is heated.

High efficiency boiler heat exchangers really need high efficiency air removal.

For some extra $$ you can make it a combination air/ dirt/ magnetic 3 in 1 device. Then you have all the bases covered with 3 high efficiency removal functions.

I agree with water that has been checked for hardness, Ph, and TDS. I also like some conditioners added for the film providers, O2 scavenging, and Ph balance they provide.

NY_Rob

If you're getting an Alpha... try to get the new version "Alpha2" as it has protection against magnetite and iron oxide particles.

roundrightfarm

Thanks for all the feedback. My radiation is wall hung modern radiators, type 33, fed by O2 barrier pex. I do have the Alpha2 pump, so good to know it has additional protection. I already have an auto air vent on top of the buffer tank and an air separator, off the first horizontal from the boiler supply, so I will probably install an independent dirt separator.

Between the boiler circ and the buffer . The buffer will take some of the garbage and the separator will get more .

Would this still be the best place with an indirect tank in the system? If I put the dirt separator between the mod con and where the indirect and boiler pump lines tee together, it would see more flow, but I also could see that the heating dist. system would produce more dirt than the indirect line and so perhaps its best to leave it upstream of the boiler/buffer pump?

hot_rod

In a perfect world, with a new system properly cleaned and filled with good water, you really should not see much of any dirt or magnetite formation. So really any location that has the ability to see all the system flow over a few hours of run time. Most fine particle seps or mag seps take multiple passes to get to the 90% plus removal.

I'm not convinced the devices being used in any of the modern ECM circs could handle an ongoing problem with fine magnetite. Where would the deposits go, how do you flush it out? IF the system has those problems or potential it needs to have a serviceable device, just like the oil filter and magnet on the drain plug of your car engine. The "barriers" or protection devices in ECMs are being advertised or market because it is a real problem out there.

Now it not the circulators fault that crud in the system is attracted to the powerful rotor magnets, they just became the ideal collection point that was not in the PSC type circ motors.

IF you do start seeing a lot of black or grey deposits or deep red color it indicates you have O2 ingress that is allowing corrosion to take place. You need to find and fix the source. With low temperature operation the pex should not allow excessive O2 ingress, no barrier pex is 100% O2 impermeable. Air vents on potentially negative pressure zones in the piping can allow air, and O2 in, pump seals on 3 piece pumps, loose valve packings, etc.

The best protection is to sample the water after a year and occasionally every few years after that. The fluid in your hydronic system is very similar to the blood in your system, it's where doctors look to find, or predict upcoming problems.

roundrightfarm

Thanks again for all the feedback. I have a followup question about connecting to the buffer tanks 1.5" NPT stainless steel male threads. All the near boiler piping will be 1" copper. Is starting with a 1.5" copper female adapter, and then sweating on a 1.5" - 1.25" reducing coupling, and then another 1.25" to 1" reducing coupling my only option, or is there a fitting out there that will make this a little more elegant. I will need to do this 4 times.

Thanks

kcopp

You can get 1.5" to 1" stainless steel threaded couplings.

http://www.supplyhouse.com/Merit-Brass-K412-2416-T304-1-1-2-x-1-Stainless-Steel-Reducer-Coupling

hot_rod

If you can find them a Nibco 603R 1-1/2 X 1 reducing female adapter is a nice clean transition.

hot_rod

Here is how a two pipe buffer would plumb. You could use standard black steel threaded tees.