No check valve on HW return line - is this OK?

[Twowaxhack]

I pretty much thought so, but no empirical evidence to prove it.

When I was under contract to have a home built here, the plumbers had a hard time understanding what I wanted to do; I simply asked for a ½" return line from the furthest point on the second floor, However they gave me some absurd price (considering the cost of PEX) and said it's because the NC code required the entire return line to be insulated. I told them I didn't think it would work then. I ended up not building the home. We wait forever for hot water in the kitchen and upstairs; primary bath is behind the water heater in the garage and is quick. Just have to live with it.

The somewhat clueless builders here say it's about energy efficiency, but one of the "energy efficiency" items they are required to install is a fresh air vent system (WITHOUT an HRV). I had that without knowing about it, then one day, I noticed that warm moist air is being sent into my office registers, and I said WTF? So they think it's a smart idea to bring in unconditioned air (hot and humid in summer, cold and damp in winter) into my conditioned living space? They think that's somehow efficient? It's ungodly stupid if you don't use an ERV or HRV, certainly in this climate. I immediately disconnected and shut down that system. My house may be built tight but the doors open all the time so I don't have to worry about any fresh air. I just don't want unconditioned air coming in my space!

I had an HVAC contractor sales walk in salesman argue with me about me not installing that fresh air intake bullshite on my system.

He got an attitude and said it’s required by the inspector and my job will fail ( my own house) and he seemed to get mad about it.

He got crazier looking when I told him I’d just tell the inspector to screw himself. I’m a grown man and if I don’t want a fresh air intake then there won’t be one.

I also live in a hot humid climate and there’s no damn way I’m going to randomly have a damper that allows air to be pulled on from outside.

A pump that’s on a timer for a few hours a day is the only way I recommend circulating water in my climate.

It’s too hot here already. Ac running 9-10 months out of the year. The last thing you want to do is introduce more heat into the building.

Rather than circulating I like to install 2-3 tankless so the pipe runs are short. No standby loss, no heat gain of the building from water being circulated.

 

[MicEd69]

I had an HVAC contractor sales walk in salesman argue with me about me not installing that fresh air intake bullshite on my system.

He got an attitude and said it’s required by the inspector and my job will fail ( my own house) and he seemed to get mad about it.

He got crazier looking when I told him I’d just tell the inspector to screw himself. I’m a grown man and if I don’t want a fresh air intake then there won’t be one.

I also live in a hot humid climate and there’s no damn way I’m going to randomly have a damper that allows air to be pulled on from outside.

A pump that’s on a timer for a few hours a day is the only way I recommend circulating water in my climate.

It’s too hot here already. Ac running 9-10 months out of the year. The last thing you want to do is introduce more heat into the building.

Rather than circulating I like to install 2-3 tankless so the pipe runs are short. No standby loss, no heat gain of the building from water being circulated.

Yep, our church expansion had to have a fresh air intake per code. And to make matters worse, one unit had to be in the front of the church, so we have this hood sticking through the middle of the nice brick front. A roll of foam rubber easily takes care of blocking the nice round duct.

And I totally agree with a pumped circulating system for "instant" hot water, with the entire loop being insulated. And using a start button to run the pump for a preset period of time to warm and fill the entire loop with hot water is the best use of electricity.

A thermosiphon system doesn't have much motive force to begin with, so I'm not sure it would work with PEX piping. I've not used PEX nor have I been around any in service. I would be concerned that the cooling in the return line wouldn't be good enough for a passive circulating system to work very well.

 

[Mitchell-DIY-Guy]

...no damn way I’m going to randomly have a damper that allows air to be pulled on from outside.

A pump that’s on a timer for a few hours a day is the only way I recommend circulating water in my climate.

It’s too hot here already. Ac running 9-10 months out of the year. The last thing you want to do is introduce more heat into the building.

Rather than circulating I like to install 2-3 tankless so the pipe runs are short. No standby loss, no heat gain of the building from water being circulated.

Good for you for telling off a person who is clueless. Too bad they didn't understand. You should have seen the look on the faces of my builder and his HVAC guy when I said..."So, in the summer, you are going to bring in moist hot air into my home, after I've created cool dry air from my a/c, and in the winter, you are going to introduce cool or cold damp air when I've just had my furnace heat it up?" The look was textbook dumbfounded. I simply shut the damper and disconnected the wires. It was a spec home and it was already here.

I live in a milder climate but similar to you @Twowaxhack. Even an ERV or HRV around here probably doesn't make a lot of sense unless one specifically has a problem with stale air in the home.

Now in Michigan (my last home), that's different. You are heating from September 1 through Memorial Day give or take. That excess heat from a loop is mostly put to good use. An ERV or HRV may make some sense particularly in the winter. Pure fresh air system? Hell no.

 

[Twowaxhack]

Good for you for telling off a person who is clueless. Too bad they didn't understand. You should have seen the look on the faces of my builder and his HVAC guy when I said..."So, in the summer, you are going to bring in moist hot air into my home, after I've created cool dry air from my a/c, and in the winter, you are going to introduce cool or cold damp air when I've just had my furnace heat it up?" The look was textbook dumbfounded. I simply shut the damper and disconnected the wires. It was a spec home and it was already here.

I live in a milder climate but similar to you @Twowaxhack. Even an ERV or HRV around here probably doesn't make a lot of sense unless one specifically has a problem with stale air in the home.

Now in Michigan (my last home), that's different. You are heating from September 1 through Memorial Day give or take. That excess heat from a loop is mostly put to good use. An ERV or HRV may make some sense particularly in the winter. Pure fresh air system? Hell no.

He understood perfectly, he was trying to sell me parts…….and was pissed off I wasn’t buying.

Houses are so tight they want you to bring fresh air into the home. No thanks.

 

[DIYQuestionGuy]

Update on thermosiphon - I installed check valve and shut off valve on return line yesterday. Pic attached. Will monitor few days and report back if any improvement in getting hot water to kitchen sink. Unfortunately, draining and refilling hot water heater opened up different can of worms. Now I'm chasing taps/cartridges plugged with debris from sediment stirred up when drained and refilled tank (e.g. dishwater water inlet valve suddenly not working).

 

[wpns]

Let us know, but I suspect you are going to have to remove the heat trap.

 

[DIYQuestionGuy]

After several days I believe the addition of the one way valve has reduced delay in getting hot water to kitchen sink. My wife says she can totally tell a difference. For me, I think it is a noticeable improvement but I suspect adding a pump would make it even better - it still take a little bit for hot water to flow after non-use for long time. Others on this thread have suggested removing heat trap as well which I suspect would make it even better but I'm still thinking on that one.