Circulator correct speed for a lochinvar cadet ???

nailian

Hi.
I have 3 heat zones/ loops running off a lochinvar cadet cdn120. Each loop uses a bell & gossett nrf-25 circulator plus an additional one that's under the boiler.
The circulator has 3 speeds and not sure to wich speed it should be set.?

Thanks in advance

SWEI

Generally speaking, the lowest speed that will deliver the heat needed on a very cold day. I'm assuming it's piped primary/secondary at that size, but a diagram or a photo wouldn't hurt.

nailian

Thanks for the response. Added images as requested.
Right now all 4 pumps are on the fastest speed setting.

Paul48

Was that installed by a "professional"? Recently?

nailian

Yes y?

Paul48

I can't see that working properly, with piping configured like that.

nailian

Not sure what you piped is wrong but it is working fine. Loops get vey hot within few min.
My main concern is the circulator speed. Just want to know what is the correct or most efficient speed for this type of setup.

nailian

The supply are the 3 lines with the circulator. 1 of the lines(main fl) which is a monoflow loops is a thicker line I think 1". If needed can get you a better angle image

nailian

Thanks Haterssguy!
First yes the house is under 2500 sq ft
So just to make sure I understand. It's ok to "play" with the circulator speeds of the 3 loops but as for the boiler circulator I should leave as is?
Currently both the boiler circulator and all 3 loops are on the fastest setting.

Let's say I do change circulator to slowest setting. What makes me determine if it's ok to leave it like that? Is it how quick the loops get hot compared to when it was on the highest setting?

To my common sense I thought that the boiler circulator speed needs to match the loops so the whole system flows at the same rate but I don't really have knowledge in this filed so it's is just my sence talking.

nailian

Great advice mate,will play Around with it.

Sound like best way to test is run each loop separate to make sure slow setting is sufficient for individual loop.
To test boiler circulator I'll run all loops simultaneously and see if All loops are hot.
I think instead of checking last room I will touch the return of the loop in the boiler room and see if returns hot after few min the system is running.

Btw I attached a graph of the boiler cdn120 and the circulator and actually according to that seams like I need to be on high speed but I know that this literature is not always right.

Zman

Good advise here.
I might add that you can tell how you are doing by looking at the boiler supply and return temps in the boilers controller (I assume that one has this display).
With everything turned on, if the difference between supply and return is 35 degrees or less, you should be fine.
According to the charts, you should be able to run at low.

Gordy

Technically if everything is clicking (flow rates, ODR, over radiation) that boiler may never see over 40% modulation if the heat loss is close to what Hat thinks.

nailian

Got it! Thanks a lot for all the advice. Let's hope I can build out the house down the road so I can utilize the system

nailian

Thanks a lot for all the help! Have a great weekend!

nailian

I just went to change all circulator a to the low setting and realized the 2 "tees" shown in the image I just attached. One tee is the supply (one on right) other is return that goes to the circulator. Are they just regular tees or are the like monoflow tees where they are designed to make the flow go in a certain direction. Cause if they are I'm Concerned one of them was put upside down and causing the system to be very inefficient.

Gordy

Regular black pipe closely spaced Ts. Thats your primary secondary decoupling Ts.

They should be 4 pipe diameters apart.

Zman

Check the arrows on the pumps. It looks like if the zone arrows are up and the boiler arrow is down, it is piped correctly. The are not and should not be monoflow tees.

nailian

Yes the pumps are in the direction you mentioned I just thought it's odd that return and supply are connected relatively close to eachother where the supply water can end up going right back down into the return

Zman

That is actually the idea with primary/secondary

Paul48

nailian............Sorry I thought I saw something different.

nailian

Thanks again everyone.
And Zman yes the controller can show both supply and return temps. The guy who installed set supply temp to 180 deg so if I see return go under 145 deg I'll put circulator on middle speed
Thanks again to you all!

Zman

What type of heat system do you have.
Your high efficiency boiler is not high efficiency running at those temps.
Outdoor reset should be setup, reducing the supply temp as the outdoor temp goes up.

nailian

I have a lochinvar cadet cdn120. The outdoor sensor was not installed. The people who installed it said they don't recommend it installed being I live in nyc and and won't heat up properly when temp are not that low yet the house feels cold.
My house is not insulated the best and I have many windows. But so far the system is beating house quick when I need it but I guess not as afficient as it can.
That's y I came here to get your great input and expertise.

Today is not the coldest day 59f and after I turned all circulators to lowest speed I turned on basement thermostat that showed 63f. After 5 min the boiler inlet showed its returning 175f

Gordy

nailian said:

I have a lochinvar cadet cdn120. The outdoor sensor was not installed. The people who installed it said they don't recommend it installed being I live in nyc and and won't heat up properly when temp are not that low yet the house feels cold.

My house is not insulated the best and I have many windows. But so far the system is beating house quick when I need it but I guess not as afficient as it can.

That's y I came here to get your great input and expertise.



Today is not the coldest day 59f and after I turned all circulators to lowest speed I turned on basement thermostat that showed 63f. After 5 min the boiler inlet showed its returning 175f

You need the ODR set up. Your installers excuse is moronic. Sorry, but true.

nailian

They are suppose to return one last time to do something so I can have them install the ODR.
For my knowledge isn't it almost the same efficiency if it's not installed? When it's not installed boiler is set to reach as set temp and will heat house quicker and then shut off. Vs when ODR installed boiler will run on lower temp when not so cold outside and will take more time to heat the house.

Gordy

NO,

The idea of ODR is to supply just hot enough water to constantly match the changing load. As load goes down so does the water temp. As load increases so does the water temp. If the existing radiation is oversized to the heat loss which the installer obviously did not do the water temps could be even lower.

Your boiler will never have a chance in hell of being more than mid to upper 80's efficiency while running temps that do not allow less than 130* return water to the boiler so it can condense.

If your going to run it as is you may as well have bought a CI boiler, and saved some money that way.

Get the ODR sensor hooked up Properly, and the parameters programmed properly. I'm suspicious that the installer may not know, and definitely does not understand the importance of this. Hence the poor excuse.

Gordy

In the perfect world where a mod/con is perfectly matched to the load, and the emitters are sized to allow for low AWT. That boiler would light at the beginning of the heating season, and never shut off till the end. Constantly modulating to the load. That's a perfect world. Can't be done with out ODR.

nailian

Ok just want to make sure you know that the cadet boiler is strictly for the heat.
I have a Rennai water heater for domestic hot water

Zman

What type of radiation do you have? Baseboard? Cast iron?