Weil Mclain ECO 155 gas piping design question

Izzydaangler

Hello,

I am a plumber from the philadelphia area. I have never installed one of these units before. I am installing one in my home and I want to get it right.

I have three heating zones and three circulators.

My old boiler was piped with an 1.5 supply header to 3 loops. Each 3/4 copper to fin tube.

The returns all returned to there own circulator into a 1.5 return header.

Can this eco be piped in the same fashion and is there controls available to handle 3 thermostats and 3 circulators?



Maybe if someone has experience with this situation they could diagram a design for me that works as per manufacturers recommendation. I cannot find anything like it in the manual.

Thank you

Zman

Sizing

How did you arrive at 155? How many LF of baseboard do you have? Have you done a heat loss?



The manual on that one is a math contradiction. You cannot have a max flowrate of 14.5 gpm and a min.delta t of 20  it just is not possible.



First determine the heating requirements, then work through the MW manual?

Izzydaangler

piping design

Hello

Its not a question of sizing. I have an established heating system in this old victorian. It was an old oil fired boiler with 3 zones.

The heater was sized correctly. I need advise from someone who has installed this heater or one like it and how they piped the three zones in using 3 circs and 3 thermostats.

Thanks

SWEI

It's ALWAYS a question of sizing

Approximately what size is the house, and where is it located?

Zman

Sizing

Of course it is about sizing.

An incorrectly sized boiler will short cycle and have reduced service life and efficiency.

You can not do a piping design without accurate flowrates and you cannot figure flowrates without sizing.

The new boiler is more efficient than the old so should be smaller. The home has likely had insulation upgrades so the requirements would have changed. Who is to say the previous installer put in the right size?

If you are going with the "bury your head" in the sand approach, put in the 155 and pipe it primary/secondary per the manual and walk away.

If you want a properly sized and designed system, do a heat loss calc.

Rich_49

How

do you know it was properly sized before ?  Old Victorian and properly sized have never appeared in the same sentence in my career . Do the heat loss , measure the installed radiation and at least see if you can lower the water temps and use the ODR . I'd be willing to wager that the boiler is at least 2xs oversized , don't forget the buffer tank my friend . Have fun with the 88% efficiency and by the way , cycling is not good unless your in the Tour de France .

icesailor

Heat Loss Calculations:

If you're not doing a complete and accurate heat loss calculation, you might as well just stick the biggest CGI, draft hood boiler you can afford and forget about efficiency. Doo it quickly before the energy/EPA codes change for 2015.

Oversized high efficiency boilers are a waste of the initial money and a waste of operational money. And if you don't read the I/O manual and install it just like shown, you might throw more money away on a quicker boiler failure that isn't covered under warranty.

You wouldn't want a 600 HP engine in your commuter small car. It would be un-drivable.

Boiler wrestler

eco

This boiler cannot control all your circulators, you will need to get a WMCR 3 circulator zone controller or similar.



As for piping,you will need to look on page 48 figure 51.



As others have said, check your sizing first.

Izzydaangler

sizing

Ok I think I understand. Shall I measure all of the baseboard for a total? What else is needed to size?

Rich_49

The Neighborhood

is where you need to visit . Taco FloPro University is an online tool free for anyone who wants to learn . Take a look and it will tell you everything you require for a heat loss . Welcome to the world of doing it right .



http://flopro.taco-hvac.com/flopro_u.html

Zman

Heat loss

The baseboard length will tell you the largest boiler you could possibly need.

The heat loss will tell you exactly what size you need.

With both pieces of info, you will know what your design water temp needs to be in order to maximize the efficiency of the new condensing boiler.

Cool stuff...

Paul48

Science

It has come so far since the old days of " sticking a big boiler in a house". Doing it wrong, you might as well stand next to the boiler and burn dollar bills, one after another. There's plenty of time to do it the right way.