Installing New Axiom Feeder on Existing Domestic Water Fed Hydronic Setup

Pollymath

Currently, my hydronic radiant setup is heated via a commercial hot water heater.

The system is fed from a domestic cold water source, through a backflow prevention valve, expansion tank and bubbler. Everything I've read says that my system is safe (provided the backflow device is functioning correctly). I'm somewhat confident in this setup protecting my house water, but I also want to be able to completely shut down the system in the summer. Which means a bacterial risk.

(I do not have temp sensors, pressure gauges, bleed valves, or drain valves on the system.)

I've determined a good investment will be adding a Axiom Feeder in place of a direct connection to my domestic water. Not only will this protect my water from bacteria in the heating system, but I could also run glycol later on too. Also gives me a little more freedom to move the hot water tank around without worrying about a water source, and lastly, the ability to see if my system is leaking anywhere.

Can I just cut my feed source pipe - maybe after the backflow valve, and connect the Axiom Feeder? As I'm just running water, does the pressure from the feeder matter?

I was under the impression that with a tank type hydronic radiant system, you could practically just pour water into the tank, seal it and go?

EdTheHeaterMan

Is there any reason you need to use open system devices on a closed system?

There are manufacturers that make boilers specifically for radiant heat; be it in the floor, or baseboard, or even big old cast iron radiators.

Some heater manufacturers even make combination systems that are used to heat both space heating closed systems and DHW open systems from the same burner.

Reinventing the wheel often ends up costing more than getting off the shelf stuff already designed to do the job.

hot_rod

Sounds like a WH dedicated to space heating?

For extra protection from backflow, you could shut off the fill valve. Assuming you have no leaks. You will know that by watching a pressure gauge.

My only issue with fill tanks and glycol is they are not sealed units, so the glycol in the tank is exposed to oxygen which destroys part of the inhibitor package.

Glycol manufacturers specifically note to keep in tightly sealed container, to prevent bthe oxygen scavenger in the blend from being consumed.

Pollymath

I've already got the dedicated/separate hot water heater and the setup complete, so reinventing the wheel is going out and buying a boiler when I don't yet need one. I'm well aware of my options to move to a more efficient method of heating water in the future when the tank dies. Currently have my eyes on a HTP Phoenix Light Duty or similar.

My interest in the Axion feeder is to eliminate any risk of bacteria infiltration of domestic water immediately.

Even if I had a boiler, I'd still want to shut down the heating system in the summer.

My concern is that I've left this fill valve open for months...potentially years. Even while the system was shut down. I don't want to risk making that mistake again, and if there is bacteria already in the system I want to eliminate any potential contamination in the future.

Currently, I've just got regular old (somewhat softened) water circulating in the heating system.

Pollymath

Here's my current setup:

hot_rod

Really no reason that you must have any fill system or valve. A low water cutoff would be advised however

A lot of fill valves, Caleffi for one, has a check inside. So with a dual check, you end up with 3 check protection. That ought to do it😉

fenkel

We use the axiom DMF150. This is used this in place of the backflow preventor. In many communities backflow preventors are not code, it must be a rpz version and inspected yearly.
Bennifts of axion system:
No direct connection to potable water supply eliminates need for backflow prevention
Make-up fluid stored in the feeder tank can be pre-treated to meet appliance manufacturers specifications
Fluid level switch shuts the pump off and enables alarm contacts if the storage tank level gets too low
Fluid drained for service can easily be put back into the system
Prevents major floods - in the event of system rupture, only the contents of the tank will be pumped into the system
Provides leak detection - dropping fluid level provides immediate notice that the system has developed a leak.