Best methods/procedures/kits for testing hydronic system water prior to flush?

np_mdbr

Hi there, I am planning on doing a full system flush on my hydronic system which has over 12 zones. I want to make sure that the quality of the fluid is appropriate, but I'm not sure where to start.

Some questions that I have:
- What are the most important elements to test for, and what should their range be?
- What type of cleaner should I be looking at when flushing the system?
- Are there guides on how to properly flush the boiler (I have an HTP-EL150N)?

I have listened to a number of "Coffee with Caleffi" podcasts on both water quality and system flushing, but am looking for something a little more specific (excellent podcasts, though!).

Thanks much.

hot_rod

Here is the water quality spec from your manual. About $250 will buy you the 3 kits you need, at a minimum.
Hardness, use a drop type kit
Ph, a small electronic stick meter
TDS, another electronic meter

Or take a sample to a nearby lab for testing. You can send a sample to Rhomar or Fernox for testing also.

Without knowing your current water quality, it is probably good enough to add the cleaner and run it for a few days, making sure every zone circulates.

Or skip the testing and do the final fill with one of these single use DI cartridges from Axiom

Last step is to add a conditioner

Rhomar and Fernox have a two can kit, cleaner and inhibitor. I think they are good for 35 gallons or so.

Once you start using chemicals you need to test and maintain them. The brand you decide on will supply the correct test kit for yearly testing.

The fill cartridges are good for 35- 50 gallon, a one time use filter.

np_mdbr

@hot_rod Thanks for your help, sorry my reply is late - lots of holiday activities kept me away from the computer (good thing, probably!).

I may not have provided a very important detail about my system - about a year ago I added quite a bit of Cryo-Tek -100 antifreeze solution by Hercules. This was due to the fact that my refractometer readings were showing hardly any freeze protection at all (it was only around 30F of protection).


After adding that solution, the readings are now around -10F, which is fine for us.

Today I flushed the boiler after priming a 1/2 HP pump with distilled water. The stuff that came out is certainly not clear, and I used Hercules test strips to determine its state.


The image shows a modest freeze protection, but also shows an "unsatisfactory" condition on the acid corrosion test.


Also, I am observing fluid leakage out of the bottom of the boiler. Not sure what to think about that!

np_mdbr

Follow-up question on flushing - what size filter should I be using during a flush to remove sediment, etc.? I don't want to throw all of the expensive stuff down the drain. I do have a 5 micron bag filter, but it's just too slow to keep up with the 1/2HP pump.

hot_rod

A few things that can cause the ph to drop. The fluid is over heated often. This happens on solar systems a lot when the pump stops or fails. Collectors can reach 340-350F. The best glycols are ok to around 325. Glycol oh can drop from 10- 7 ph in a year if it is over heated.

The other problem is mixing glycol on site with tap water. The inhibitor package blended in hydronic glycols gets depleted almost immediately from the hard blend water.

All the glycol manufacturers suggest distilled, RO if DI water for blending.

If not but the pre blended glycol, use it right out of the bucket, no mixing on site

Another cause is oxygen ingress. Non barrier Pex is an example. The package includes an oxygen scavenger chemical. Once that is depleted ph will drop. O2 can be getting into a system through a misplaced auto float vent.

Glycol put into a dirty, rusty system can compromise it also.

Depends on what you are trying to pull out as far as filter micron size. You may need a larger BigBlue 20 cartridge to get higher flow will filtering that sludge out.

If you could let it sit for a day, most of the dirt will settle out in a bucket or plastic barrel.

You can add new inhibitors if the ph hasn’t dropped too low. Dow suggest replacing glycols once they drop into the 7,s ph range.

Glycol is slippery it tends to leak out of joints that water doesn’t 😳 Threaded joints, some press connections, stem packings, etc. That leak looks a bit more serious?

I’d be tempted to run a hydronic detergent in the system before re-glycoling it. Rhomar, Fernox or other.

np_mdbr

@hot_rod Thanks for the advice! Those testing devices are on order now.

I'm at the point where I want to start over with the fluid that's in this system. I am pretty sure the owners before us were using tap water and not treating anything with inhibitors, etc.

Where would I start with this, i.e. "starting over"? Obviously, draining the system is part of it, but is there a specific technique that's better than others?

One of the Caleffi videos recommended using a full 3/4" diameter hose to drain/flush the system because of the superior flow, however, this system has regular garden hose-type faucets, which restrict the flow at the inlet/outlet to a very small opening. I assume this would defeat any attempt to use large-diameter tubing to connect the system to the pump?

hot_rod

if you have 45- 60 psi or more from a faucet to flush, a regular washer hose can flow 8-10 gom. But if you are flushing with a fill valve at 20 psi or more, the larger hoses will give you much better flow.

3/4” loops flush well with 5-6 gpm” and larger systems like 10 gpm or more. The Caleffi 573 will flow around 5 gpm if you have over 30 psi at the inlet. Most fast fill valves will flow around that.

The reason is we want the flow velocity, measured in feet per second to be 5 or higher to move and flush any solids or sludge sufficiently.

It depends on how much info you want on the current boiler water. Rhomar and others will accept a mailed sample and test for hydronic specific issues.

Basic diyers could use a hardness test kit, TDS meter, and a ph meter to get a good idea of what is in the system