Solia boiler question?

Eric L._2

Replace and converted coal boiler about 2 years ago in my relatives house and it heats fine but I can't get the water temp of the boiler to get much over 140 degrees. I ran a heat calc and I chose the appropriate size according to that. Like I said it heats fine but there are some big pipes supplying all the rads. I believe the feeds are 2 inches with 1/2 inch branches.What could cause a boiler to not reach set temp of 180 deg? Thanks



Eric 

Robert O'Brien

No

primary/secondary? The boiler will be destroyed by condensation without protection from the low water temps

RobbieDo

Cold temps

What type of boiler is this? Need some more info on this.

Eric L._2

It is a Solia Boiler model

SL375 0.75

Beckett AFG .60 x 70°B

105,000 91,000 79,000 526 85.5 3.6 300 21” x 33” x 22”



I piped it just like the manufacturer recommended and it does have an adjustable bypass to divert some hot feed to cold return but even with that my temps don't get up much over 140 degrees.

Robert O'Brien

You

need primary/secondary or a low loss header.  You can't run a non condensing oil boiler with those temps,it will have a VERY short life!

RobbieDo

Water temps

I looked at the Mfg recommended piping. Do you have a indirect on it? Running at that return temp isn't good. What did the Mfg tell you?

Jason_13

Piping

What type of radiation is in the building? What was the heat loss. Do you have the proper nozzle per the heat loss?

If you have a large water volume system, which it sounds like you do have, you may need a boiler bypass. The boiler can only handle a certain amount of flow. There is a minimum and maximum flow.  Exceed that flow and the water temperature may not get high enough. A boiler bypass will bypass water around the boiler and back to the system.

Steamhead

It may be

that the water temps you are seeing are all that's needed to heat the house. Many older hot-water systems run like that.



In your case, I'd favor an injection-loop setup. This uses a small variable-speed pump to move some water from the boiler loop (which runs at a high temperature) to the system loop (at a lower temperature). The pump speed is regulated by an outdoor-reset control which can adjust the system loop temperature according to the outdoor temperature.



Outdoor reset is a proven fuel saver. With this setup you'd accomplish two things- boiler minimum temperature and optimum system temperatures.

RobbieDo

Temp

Have to figure out from the Mfg what the min temp of the boiler is, I install Buderus and they allow low return temps, not sure on this boiler. Like Steamhead said you need a injection loop to keep temps to the boiler up.