Need help ! Takagi slow flow issue

HeatDummy

Hi;
I'll be honest, I've made some mistakes, but this seems the worst by far, and I think I've gotten way over my head on this one. Any wisdom would be greatly appreciated.
The system is was an attempt at a 1200 sq ft radiant under floor system, using a Takagi T-H3-DV-P ODWH with 1/2" O2 barrier PEX 8 Loops all at 250', with a grundfos alpha I ECM circulator.
So far the highest observed flow that I can achieve is 1.8gpm. I assumed I had made an error on the pressure losses based on the flow rate for the water heater and upgraded the circulator to a grundfos 26-99F (max 32ft of head) thinking that the higher head would help the underestimated situation.(at this time the system pressure was around 35psi and this didnt help either) still only able to get 1.8gpm.
Reading some of the wise threads on this site, It sounded similar to the snow melt system with the T-D2 takagi heater, and anticipated the required low pressure valve situation and increased the pressure to 50psi, assuming the pressure relief valve limiting the full flow of the water heater. Sadly no luck either, but does the heater board need to be reset or is it reset every time it is unplugged?
Some of the remaining things that I have yet to confirm, is the low gas line pressure(the propane company ran the new 3/4" line but first 2' of it is still 1/2" which I found odd but I'm not a gas expert, or some possible venting issue, but I guess I'm clueless since I followed all, well most of the guide lines(the current vent is 30 ft with a concentric discharge).
Also not sure if I put the expansion tank in the right place, but I can easily relocate that to output of the ODWH as both sides have an air separator as shown
I've attached some pictures of the system. I'm still leaning towards a silly miscalculation on my part and it's got something to do with the water heater, but clearly it wont be the first time I've been wrong.
With the System operating, the pressure readings(psi) are 41-Circulator-52, return at 48 and the expansion tank is at 48. Delta T is at 22 Degrees.
Thank you.

Snowmelt

I see what's wronge.
The pump is on wronge side you have to pump into the heat exchanger
You need to also make a primery / secoundary loop
I would also like to see all your piping 1 inch.
Where are you located?

HeatDummy

Hi Snowmelt;
I'm located in CT near Hartford.
Forgive me, but I'm curious about the reasoning for behind your recommendations, only because everything I've looked at so far tells you to put the circulator towards the loops and not the boiler, or this is the case for ODWH's? (just trying to understand, it is doable and wouldnt be too bad)
As for all being 1", also doable but I elected for 1 1/4" for the sake of being able to add an additional smaller independent zone with its own circulator where the T's are fitted(as marked in the picture below).
Also;
Would you advise for relocating the expansion tank as well? to before the circulator?
The reason why opted out of the primary/secondary loops was to avoid having to deal with the control and mixing aspect of the processes, and also hoping to keep it as simple as possible. Apparently the design guide I used isn't what should have been used.
Too bad that the majority of the setup was useless to this point and that will be a fair amount of work. Should've seeked advise before the start.
Thank you very much for your help, I really appreciate it.

Snowmelt

Forgive me, but I'm curious about the reasoning for behind your recommendations.
Answer about 7 years of working on takagi units. I know how they work, how many btu's are you trying to heat up, how many gpm are you trying to run into the unit.

only because everything I've looked at so far tells you to put the circulator towards the loops and not the boiler, or this is the case for ODWH's?
Answer every takagi that I have working has the pump going in the machine. Also you have to pump away from the expansion tank. If you use primery secounday I would put the expanion tank on the loop with the snowmelt side.

As for all being 1", also doable but I elected for 1 1/4" for the sake of being able to add an additional smaller independent zone with its own circulator where the T's are fitted
Answer that was my fault 1-1/4 is fine, do you know why your using 1-1/4 or are you just thinking bigger is better?. Again how many btu are you using?

Would you advise for relocating the expansion tank as well? to before the circulator?
Answer. I said it already, yes pump away from the expansion tank. But the question I have for you is do you know why we do that in the heating industry?

The reason why opted out of the primary/secondary loops was to avoid having to deal with the control and mixing aspect of the processes, and also hoping to keep it as simple as possible. Apparently the design guide I used isn't what should have been used.

Answer
What do you mean controls, use a taco relay and you can have two pumps operating I'm having a tough time understanding deal with controls and mixing, kinda reminds me of what I tell my girl friend about laundry. The machine cleans the cloth it's not like your scrubbing a shirt on a rock in a river. The mixing is done with the water heater and primery secoundary piping. I personally would like to see the taco hydronic seperater or the caleffi seperater, the reason I like to see them is the water mixes and slows down.
Your primery loop will be around 4 to 5 gallon per minute, your secounday will be closer to 10-15.
Unless your load is under 50,000 you should use p/s.

Too bad that the majority of the setup was useless to this point and that will be a fair amount of work. Should've seeked advise before the start.
Thank you very much for your help, I really appreciate it.
Your welcome, I have more then a few applications out there. I have one question, what do you use to turn the snow melt on or off.

Snowmelt

Three pics

HeatDummy

Answer about 7 years of working on takagi units. I know how they work, how many btu's are you trying to heat up, how many gpm are you trying to run into the unit.

According to multiple heat load calculations I only need about 35K-40K and max 50K BTU's for the first floor. Given the performance at 1.8gpm, if I can get 4-4.5gpm it would work. New construction home, I had paid the builder to install a geothermal system, but I guess he decided he wasn't going to do it and hence I'm stuck with only electric baseboard and at $600/month in winter, decided to install this, long story lawsuit still pending.


As for all being 1", also doable but I elected for 1 1/4" for the sake of being able to add an additional smaller independent zone with its own circulator where the T's are fitted
Answer that was my fault 1-1/4 is fine, do you know why your using 1-1/4 or are you just thinking bigger is better?. Again how many btu are you using?
I decided to use 1-1/4" because it can support a max flow rate of upto 16 gpm easily and at 1" the max would be around 10gpm(max 2 zones for the house), so just more margin if I decide to add additional zones in the future, say if I finish the basement.


Answer. I said it already, yes pump away from the expansion tank. But the question I have for you is do you know why we do that in the heating industry?
Something to do with constant pressure point?(sorry not too familiar with the industry)



Answer
What do you mean controls, use a taco relay and you can have two pumps operating I'm having a tough time understanding deal with controls and mixing, kinda reminds me of what I tell my girl friend about laundry. The machine cleans the cloth it's not like your scrubbing a shirt on a rock in a river. The mixing is done with the water heater and primery secoundary piping. I personally would like to see the taco hydronic seperater or the caleffi seperater, the reason I like to see them is the water mixes and slows down.
Your primery loop will be around 4 to 5 gallon per minute, your secounday will be closer to 10-15.
Unless your load is under 50,000 you should use p/s.
Sorry for the misunderstanding this is not a snowmelt system. According to every scenario, I don't think I need the primary secondary setup, as if I use zone priority for the first floor which is where we spend the bulk of our time, and the second zone being just the master bedroom I dont think it would need more than 50K BTU.

Thank you again for your insight, as soon I go ahead and shuffle things around I will let you know how it turns out.

I have to apologize but I have zero experience with snow melt systems always thought about it, but whenever I've looked into it, I've always thought of using the Donfoss 224. Sorry for not being much help.

Rich_49

I wish everyone would stop trying to use water heaters where a boiler should be used . Water heaters are best used in an open system like they were intended for .
Was this worth the problems you are going through at present . Your knowledge , integrity and profit are all in question now . this customer will probably not ever recommend your services and in fact may tell 100 people that you suck even though that may not be the case .
Your heating source has a rather high head loss through the exchanger because it was meant to be installed in a system with higher pressure . How many GPM do you require on your system side ? What Delta T is the system designed for ? What is the max temp of the system ? What is the head of the system ? All the head loss for the entire circuit must be added together . You must separate the circuits and use 2 circs . Just a guess that the 26-99F is capable of moving 1.8 GPM at 30 Ft hd . The ft head in the source portion of this system is north of 20 .

http://takagi.com/media/19483/240-340-540-TH3J-TH3S-TH3-Spec-Sheet-TRGSS01512.pdf

This is all part of proper system design . If you have not already and just had a bad day , unlikely . You should spend some time in a classroom with someone like John Barba or at a minimum check out the FloPro University videos and complete the quizzes at the end of each . You can easily avoid this in the future and become a quality designer / installer and start answering the questions as opposed to asking them .
Do the primary secondary , this will lower your PD through thew water heater considerably . Purchase a Caleffi Sep4 and get rid of the 2 air elimination devices you have there now . This equipment will make your life easier and allow for dirt separation , air elimination and hydraulic separation . Put the boiler pump on the return (pushing into) the water heater and leave the system pump where it is on the supply side . Use your ECM circ , if you still have it on the system side and get the right pump for the flows and pressures you'll need on the water heater side . Don't forget to size everything for your future load also so we don't have to do this again .

Snowmelt

Well put, just last week I had 2 calls for navian combo units where there wasn't p/s and that's right in there manual but that's ok, just means more money for me.

icesailor

@Snowmelt:

There's never enough time to do it right. But always time for someone else to do it over.

I'm starting to wonder because of all the problems that are showing up here, are with improper equipment, bought by homeowners from Internet Supply sellers, that don't have the technical know-how that we professionals, that supply the equipment, get from our wholesalers.

The manager of the company I did business might tell someone that a gas water heater isn't a good substitute for a gas boiler. If you choose to ignore the advice, you'll be on your own.

Stand at a busy counter for an hour. Listen to the stories from homeowners or rookie installers. There's a parallel universe out there. How do you give a price on something figured out by others, that you had no input in deciding. and the owner of the equipment wants to have three people quote prices to install it? That becomes a race to the bottom. Who can do it for the least and win the contest of who will loose the most money.

Stop The Insanity.

Snowmelt

Ice your right, No one wants to pay.