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Originally Posted by terpfan_

Would a tube in tube have been a better idea than plate xchanger? I will never go back to a regular water heater. My tankless rinnia was one my best investments.

Doesn't matter. He doesn't have enough boiler for more then 6 GPM at a 70°F temp rise no matter what heat exchanger he uses.

Originally Posted by terpfan_

Would a tube in tube have been a better idea than plate xchanger? I will never go back to a regular water heater. My tankless rinnia was one my best investments.

his problem is he does not want to spend the money once to do it right the first time. he chooses to rely on his theory that we all told him would most likely not meet his demands. now he will spend the money and time twice. as was stated by someone previosly, he should have been an engineer.

Would a tube in tube have been a better idea than plate xchanger? I will never go back to a regular water heater. My tankless rinnia was one my best investments.

Originally Posted by firecontrol

The OP starts this thread by saying "My highest priority is having adequate hot water if both my wife and I are showering at the same time. Secondly would be space consumption of the new device, and lastly is fuel consumption." He also states "I have a very broad range of general info about most residential systems and components, and tons of "theory" about how systems work. I understand in theory how these work, and know that it SHOULD do the trick. Again, not being an HVAC specialist or expert, I could really use some direction." What he failed to mention in his first post was the priority he had assigned to the cost of heating the water. Reading all the subsequent posts points to the fact that it should have been #1, but that's just a theory of mine.

As beenthere posted, the math is what is going to point the way to what will and won't work. Having a theory about something is the same as an opinion. When the math backs up your theory you have the proof.

Over 25 years experience in this business tells me that the proof in this case will be when he installs what his theory has told him will work only to find out that the "it works" part is a lot smaller percentage than what the "I needed it to do this" part is.

Very well put. Lol

after putting us down for helping, i don't think we will hear how it worked for him. especially when his theory does not work to his demands.

It was a loosing battle to begin with. The HX will work, hot water will pass through it and will heat water on the secondary side. That's what they do. Will it perform to his standards? Hope we hear back

The OP starts this thread by saying "My highest priority is having adequate hot water if both my wife and I are showering at the same time. Secondly would be space consumption of the new device, and lastly is fuel consumption." He also states "I have a very broad range of general info about most residential systems and components, and tons of "theory" about how systems work. I understand in theory how these work, and know that it SHOULD do the trick. Again, not being an HVAC specialist or expert, I could really use some direction." What he failed to mention in his first post was the priority he had assigned to the cost of heating the water. Reading all the subsequent posts points to the fact that it should have been #1, but that's just a theory of mine.

As beenthere posted, the math is what is going to point the way to what will and won't work. Having a theory about something is the same as an opinion. When the math backs up your theory you have the proof.

Over 25 years experience in this business tells me that the proof in this case will be when he installs what his theory has told him will work only to find out that the "it works" part is a lot smaller percentage than what the "I needed it to do this" part is.

Advantage of an indirect over a plate HX. If your demand exceeds the boiler or HX's GPM even for 1 minute, you end up with an unhappy wife in the shower. The Indirect will allow you to have an over draw for a short period of time.

The largest MI is 211,000 BTUs output. Thats only 6 gallons per minute at a 70°F temp rise(120-50=70). Your shower heads will probably exceed that by a lot.

Before you decide on how to heat the water. You need to know how much for how long and at what temp rise. I didn't see any of that info in any of your post.

You asked a question and were given several solutions to your problem howie, don't be mad because you don't like the answer. No one here stands to profit one way or the other so since you've allready made your mind up that all of us are wrong and your right give that plate heat exchanger a try and let know how it works. Post some pics of your install too cause reading is hard.

Prices are not permitted.

This thread was entertaining! Sounds like Howie should be a plumbing engineer!!

You sound like the common home owner. No EXPERT here wants to help you because your difficult.

We deal with you home owners all the time, no need to waste our time because you already have your mind made.

Always wants to spend $20,000 on a kitchen or bathroom but skimp on the important things in the home like the HVAC equipment and water heaters.

I don't like home inspectors because most of them are idiots. Anyone can become a home inspector.

Please explain how we've been doing it wrong for decades. My customers aren't complaining. Actually they are very comfortable and have probably been soaking in the tub for a few hours.

Good luck with your project.

Sorry everyone, I really thought I was going to find highly trained, really smart, experts here. Apparently I was mistaken. For the few of you who had relevant thoughts or ideas to share, thanks so much. For everyone else, good look with your expensive indirect fired water heaters, that are great, but only for the CORRECT application. I hope you can figure out at some point where and when that is, clearly you haven't yet. I'm horribly disappointed with this. You keep saying the same thing "that wont work, but this will". Yet you can not support your claims, or at least haven't chosen to. Sorry I bothered you all with an idea that you weren't completely familiar with, which is CERTAINLY a really good reason to keep knocking it. I guess this is why most home tradesmen don't like home inspectors, home inspectors actually know things. It might make the lame, very mediocre tradesmen have to do something different. "Well I've been doing this for (fill in the blank) years!!!!" I hear that all the time. Well good for you, that you've continued to do something incorrectly for DECADES!!!! Some of you seem to know what you're talking about, the rest of you should really go find a true "expert" and learn something. Thats it for me, have a good night.

plate exchanger will never do what you want.
2 40 gallon tanks will take up twice the room of and indirect and probably last 1/2 as long.
a good indirect hooked up right would probably give you a higher first hour recovery than the 2 40 gallon tanks.


good luck...

I have a 36 port pex manifold very close to the water heater and boiler. I have multiple runs already installed for the shower alone. I know I could run a return loop through the manifold, which would be easy, but what that really do anything?

If you are worried about pressure drop with the plate heat exchanger why couldn't you run a hot water recirculation loop? I know the main obsticle is volume but a recirc loop might combat the pressure drop problem.

Thanks for all of the info everyone.

Joehvac25, I am also 99% certain that you will not, and the pressure drop is a very important and relevant concern that had not crossed my mind, and that alone may be the "deal killer".

Philjafo, I agree whole-heartedly, and will go with another 40 or 50 gallon if the brazed plate turns out to be a bust. I'm hopefully going to find people with actual experience, as they are supposedly rather popular/common in parts of Europe.

Gravity, thanks for the drawing, you're quite an artist. You should maybe read all of the previous posts. Maybe then you'll stop just saying the same thing over and over without any further information or explanation to stand behind it. I believe there has been some very good points and counter points relevant to the discussion that it seems you may have missed.

So, You will never be happy with your plate heat exchanger.

Your boiler needs to be zoned. Get it zoned.

While your at it, put in a indirect.

When piped properly, when you need hot water in the summer, the boiler will run for a few minutes to heat the indirect. It will not be a waste because of how it's piped. The heat loss will be nothing. If you go with the buderus you could have hot water in that tank for weeks before it would need to warm back up. Here's a little drawing. the water in the DHW loop is minimal which will only need a few minutes to warm up the water.

Attachment 338111

Second 40 gallon conventional water heater, its the most common solution to high demand that I see because it works well. No need to reinvent the wheel, its not plumbing on the space station right.

Hell I don't care what you do because I'm 99 percent sure I won't profit off it but I think the braze plate won't work that great. One other factor is the pressure drop across the plate to plate, will you have enuf to feed your big shower heads after the fact? Tell us how it works when your done!