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

epark2014

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

Does it work? What's the issue?

Kaos

Is that domestic hot water flowing through cast iron pumps?

hot_rod

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

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

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

bjohnhy

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

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

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

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

epark2014

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

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

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

EdTheHeaterMan

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

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

SuperTech

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

Ok, if space heat only then it makes sense.

Your main issue is the tankless is high pressure loss. Those pumps for the two zones are not powerful and they will fight each other, unless perfectly balanced, only one will get flow which is probably what you are seeing. I'm guessing that is why some of those flow T splits were done, a strange attempt at balancing flows.

I think that loop that goes through the flex stainless to the drain port on the tankless is a way to purge the system (lets you back purge the tankless if you close the other valve).

The simplest solution is to add a 3rd circulator and create a primary secondary loop where the 3rd pump is just for the tankless unit. This pump gets triggered when either zone calls for heat. Similar to this diagram:

Another option is to add a high head circulator (Taco 009) just for the tankless and replace the existing ones with zone valves like this (this shows a electric boiler, but works the same):

It also doesn't look like you have a proper fresh water feed. There needs to be backflow preventer (aka, fancy check valve) before your pressure regulator. That in-line check valve on the manifold is not to code.

bjohnhy

Picture 2

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?

I'm betting there was another pump there between the far right red lines. That pump failed. Instead of replacing a new pricey pump, someone decided to just just T that loop up to the working pump. Do you think both those loops are heating adequately? Right angles themselves are not an issue per se.