Confused about home Hydronics heating system. Can some help me decipher whats happening?

epark2014 · October 16

Magenta is the city water (usually closed) but there is a loop in it? Should I be turning one end of the flexible tube to make it not a loop?

Why do the red tubes start as two, join as one into the circulator, and then back to two? Are the right angles an issue?

These are the return lines. What is happening with the green line? It comes down as one, and then split into two again? Could one half of it be removed?

delcrossv · October 16

Does it work? What's the issue?

Kaos · October 17

Is that domestic hot water flowing through cast iron pumps?

hot_rod · October 17

The mnagenta is just the fill system that maintains the pressure. It also flows as you purge water out.

What is it you are trying to accomplish? A purge?

epark2014 · October 17

It mostly works, but the heater still struggles to keep up during the winter. I had to replace my expansion tank yesterday, as the other one went bad after 3 years or so, so I would assume something went wrong to cause the tank to go bad this fast.

I'm just confused about some of the design choices, and am wondering if the oddities that I see are inefficiencies that can be removed to improve performance, or if they were installed for a reason. I don't believe a licensed plumber installed this hydronics system, or at least there were modifications made after the initial install, which is why I am questioning it in the first place.

1. Picture one, the magenta line is the water line into the system, which usually stays in a closed position as it's a closed loop. My questions is that the line that feeds out hot water from the boiler has two exit points right on top of each other, that basically do a full circle. Should I close the valve on one of the feeds so that the water only runs in one direction through the system?

2. Picture two, are all those right angle connections on the red pipes causing water to not flow evenly between the lines? I would assume that water follows the path of least resistance, meaning that the hot water mostly goes straight up the left straight line, instead of towards the right side with their two 90 degree bends.

3. Picture three, honestly I just don't get why the green return line would split into two lines. Is there a good reason to do that?

I was looking at a lot of other pictures and videos of other home hydronics heating systems, and they look much cleaner and organized, so I'm just struggling to understanding my system 100%.

Kaos · October 17

All this plumbing connects to the Tagaki. Is that for space heat only or does it also do your hot water?

bjohnhy · October 17

Did the manual inline valve at he bottom of the green line become seized in closed position? So later it was modified with a bypass through the original purge valve? That stainless steel flex tube looks like an updated bypass to me.

The only cast iron I see is the gas line.

GGross · October 17

Looks liike a takagi non-condensing tankless water with questionable venting. Not sure how you manage to get enough flow through it like that. What is the boiler next to it hooked up to?

epark2014 · October 17

https://forum.heatinghelp.com/discussion/comment/1814747#Comment_1814747

It is for space heat only. There are separate boilers for hot water.

epark2014 · October 17

Yeah I think that's the most likely case, but it looks like the bypass is also soldered on the copper, so why not just unsolder/resolder the valve? Could have just been a lazy fix, but if it works then I won't touch it.

epark2014 · October 17

What makes the venting questionable? Would improving venting improve the output of the boiler?

Also, the house is a duplex, and each half has it's own home heating system. The boiler next to mine is the neighbors.

mattmia2 · October 17

Can you post the pictures without the lines drawn over them? I am having trouble seeing the piping behind the lines.

EdTheHeaterMan · October 17

Another water heater that is being used as a space heating boiler, and it does not work properly

I wonder why?

Takagi Space Heating Boiler

Based on the search results, Takagi’s products are primarily designed as tankless water heaters, not space heating boilers. While some users and installers have experimented with using Takagi tankless water heaters for space heating purposes, Takagi’s own documentation and marketing materials do not explicitly promote their products as boilers for dedicated space heating.

In fact, many of the search results highlight the limitations and potential drawbacks of using Takagi tankless water heaters for space heating, such as:

Lower efficiency compared to traditional boilers
Code and insurance issues
Limited capacity
Modulation around flow rate and temperature, which may not be optimal for space heating

So, in this case, I might make a recommendation that someone that has experience with this problem offer this homeowner a price for a proper boiler and a proper system design that will work as itr is designed in order to do space heating. This setup is always going to be problematic, even if it worked in the past, the piping design and the fact that this is not an open system with pressures above 30 PSI to actuate the flow switches that will make that burner operate as it was designed. There are boilers that are designed for this purpose.

You wouldn’t use a Cast Iron Burnham or Weil McLain boiler as a water heater, Would you? …Maybe if you like rusty water to shower on you

hot_rod · October 17

Is the cast iron boiler still connected to the heating system? The Takagi just for DHW?

SuperTech · October 17

Unfortunately three years for an expansion tank to fail is not uncommon.

And I agree with Ed. If you are using a Takagi for space heating forget about anything with the piping. Nothing with that has anything to do with the problems you are experiencing. You are using the wrong tool for the job. We see posts on here all the time from frustrated homeowners who either made the mistake of installing a Takagi for space heating or moved into a home where someone foolishly installed a tankless water heater instead of a boiler.

Kaos · 1:02AM

If space heat only, than it is starting to make sense.

The issue is you are using a high pressure drop heat source with two undersized pumps in parallel. Since they will fight each other, unless they are perfectly balanced, one will get the bulk of the flow which is I think what you are seeing. Some of those T splits are a misguided attempt to flow balance, which doesn't sound like it is working.

Your options are to add a 3rd high head circulator pump (ie Taco 009) and convert to a proper primary/secondary type setup like this diagram:

or

Add the high head pump and replace the existing pumps with two zone valves. Something like this (shows a resistance boiler but would work the same in your case).

Your fresh water feed also has issue. There should be a proper backflow preventer before your pressure regulator. That in-line check valve on the manifold is not to code.

Confused about home Hydronics heating system. Can some help me decipher whats happening?

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