Radiant Sysytem Problems

Rockat98

Just purchased a home with radiant floors.  Dunkirk Boiler XEB-4 with a TACO RMB-1 leading to manifolds with 4 zone controlers.  The boiler seems to be short cycling, thoughts?  The RMB-1 is on the set point mode. I also have wood floors and would like a recommendation for tempeature settings.

Thanks

SWEI

is the outdoor temperature sensor installed?

The RMB should be varying your supply temp based on outdoor air temperature.



You may need a buffer tank to stop the short cycling.  Can you post s few photos of the boiler, RMB, and associated piping?

Rockat98

Which setting is best to be using?

I will post some pictures tomorrow when I get back into town. You mention the outdoor air temperature, should the rmb be running under the outdoor reset control?

Rockat98

No outdoor sensor with unit

there is no outdoor temperature sensor with the current setup

Rockat98

No outdoor sensor with unit

there is no outdoor temperature sensor with the current setup

SWEI

outdoor reset control

Will provide maximum comfort by reducing overshoot and anticipating demand.  You want it.



A buffer tank will quite likely be necessary in order to prevent the boiler from short cycling.  Do you have a heat loss calc?  What size is the boiler?  Is it also heating domestic hot water?  Again, pictures will help.

Rockat98

the boiler

is 112,000 btu's/83% efficiency.  No heat loss calculation.  The boiler is not heating domestic hot water.

Rockat98

Boiler/RMB

Here are some pics. 

Paul Pollets

Pics

I get dizzy when looking at the pics...I'd re-pipe the boiler with the pump on the supply, rather the the return and properly support the piping. This is a good case to show why not to use Pex piping on the "near-boiler" piping. Hopefully you can find a good local contractor who know's how to do it right and make corrections.

Eastman

Hard to tell from the photos, but

It looks like the RMB-1 is not piped into the primary loop correctly.

Mstrplumbr

What a shame

Judging from the prescience of shark bite fittings, wiring, and piping, this was definitely installed by someone who had no business installing. I would call a reputable heating contractor before you damage the mixing block

Mstrplumbr

What a shame

Judging from the prescience of shark bite fittings, wiring, and piping, this was definitely installed by someone who had no business installing. I would call a reputable heating contractor before you damage the mixing block

Paul48

A Mess

The air scoop is useless, the way its piped.

Rockat98

Well,

Thanks for the great suggetions and thoughts.  I too can see that the job was, well, poorly done.   I actually met the plumber who installed the boiler.  WOW!  Wood Chuck!  I also looked at the boiler the previous owner had taken out: seems the old farm boy wasn't a fan of safety features.  

From my research and others that have given input, I need to redo the entire setup. I am worlking on heal loss calc.  What are some other items that you as pro's would also consider with the reconfiguration of this system.  I have looked at the tubing, insulation and conenctions under the floor and they look well done. 

 I have been fixing up old homes from the foundation up for 20+ years and am confident with the plumbing issues that I am facing, but would like to hear your thoughts.

Eastman

Does this system actually heat the house?

This is the primary heating system?

Rockat98

This system is only heating part of the house.

At this time the system is only heating 1/2 of the house and the other by electric baseboard

Eastman

For starters...

Is that O2 barrier tubing?



What is the plan for electric, is that going too?

Rockat98

Data on Pex

1/2" O2 barrier with aluminum track.  I am planning on getting rid of the electric in the spring when I gut the old part of the house.

Eastman

Concerned about the floors

Are you thinking of putting underfloor heat where the electric is?  The extra btu demand as the sole source in an older farmhouse may be to much for underfloor, particularly if you have nice wood floors.  Cycling frequently at high temps can loosen them up.  Ideally, this part of the system would have a constant supply of heat, mixed appropriately based on the outdoor temp and configured to limit surface temps to a safe high limit.  With a non modulating boiler, a buffer tank is imperative.  You may need to use panel rads, baseboard, or forced air as a second stage to add additional btus.



Based on the workmanship in the photos, I think you would be extremely lucky if that boiler were to prove of appropriate size.  If it doesn't match, sell it.  The worst thing you can do is try to salvage an over sized CI boiler.  If you get another non-mod, choose one that is a step down from your heat loss.  Don't add anything for domestic hot water.  You do not need to do this for residential applications unless you have bizarre usage habits.

Rockat98

More Toughts

I am going to remove all the electric baseboard.   I have alrady jacked the house up and resupported the foundation. I am going to gut the house from the basement to the roof rafters.  The area that will retain radian is an addition to the main part of the farm house.  I will be puttting in all new floor joists an dsub floors.  My plan is to use an above floor sleeper system for the radiant.  The boiler is  112,000 btu's which I actually think will be adequate.  I am already planning on a buffer tank