Oversized boiler

cynthia07104

So it turns out my boiler is way oversized for my home. Currently have a 250,000 BTU when I only need a 150,000 according to the company that came out. The current boiler was installed last year so naturally I’m quite upset as the installer obviously miscalculated everything. My questions would be who could I market such a big boiler to, and would it be okay to use it one more winter as I can afford to shell out another $ for another NEW boiler at the moment.

ImYoungxD

Is this gas or oil? Oil heat can be down fired with a smaller nozzle. If gas, you should probably stick with it instead of buying another one.

What are your issues with the oversized boiler?

SlamDunk

Since it is only a year old, I would start with the installer. There should be a level of trust when you contract someone to do a job. You should expect the contractor to size it right. That said, over sizing is common.

You can use it as long as you like and if you find a really good boiler person, they may be able to down fire the burner, maybe- I'm not a pro- but maybe install a smaller burner for considerably less cost.

It's worth asking when looking at the cost to replace

cynthia07104

It’s a gas boiler...

Called someone in because we noticed our header was misconfigured and one of our radiators does not heat up completely. Other than that I don’t have an issue. Being a first time home owner I’m not sure how bad having a boiler so oversized could be. As per the rep that came out we have an EDR of 432.5 and the boiler gives out 634.

Jamie Hall

The hassle with an oversized boiler -- which is dismayingly common -- is that it won't be quite as efficient as it might be. The more oversized, the more hit you take on that. As @ImYoungxD said, it may be possible to downfire it... some. But that takes a really good technician to get right.

The hit on efficiency, though, is nowhere near big enough to justify changing out a nearly new boiler.

You ask who might use such a big boiler? Lots of places. The main place I care for, for instance, has a boiler with a net output of about 350,000 BTUh... and is just barely big enough.

cynthia07104

@Jamie Hall I was given the option of downfiring it but was not sure if i should mess with it. I kept fearing causing more problems in the long run with modifying the boiler. If the only issue would really be the effiency of it I think I can manage that as my utility bill has been the lowest I have ever paid and now I’m in an actual house. I agree that effiency hit won’t justify a $ bill.

@SlamDunk I would go back to the company but they turned out to be flip floppy and are no longer in business.

SlamDunk

That blows. At the very least, you should have a burner tech clock your gas meter to make sure you're not over firing the burner. No need to burn more fuel than you have to.

Fred

Depending on the boiler, it can have a two stage gas valve installed that will reduce the output to about what you need, in low fire. You need a professional to do that installation and combustion test to make sure it is set up properly. Being that over-sized it will definitely short cycle when the weather gets cold enough that the boiler runs for longer cycles. That puts some additional wear and tear on the controls as well. Where are you located? There are many great steam guys on this site that know how to install a two stage gas valve.

cynthia07104

@Fred I have a Williamson boiler... the rep that came out gave us the option of adding a two stage valve for what I think would be a reasonable amount. It definitely beats replacing the boiler. If if were you in my situation would you leave as is or change out the valve?

Fred

cynthia07104 said:

@Fred I have a Williamson boiler... the rep that came out gave us the option of adding a two stage valve for what I think would be a reasonable amount. It definitely beats replacing the boiler. If if were you in my situation would you leave as is or change out the valve?

I would go the two stage gas valve route in a heartbeat. It's going to save you fuel cost, and wear and tear on the boiler controls.

EBEBRATT-Ed

Yes, I agree. It isn't critical to put the two stage valve in but you will save fuel and increase efficiency and have smoother operation. Especially with a new boiler I would do it

cynthia07104

Thanks for all the input. I have scheduled to have the two stage valve installed in 2 weeks. It beats getting another new boiler.

SlamDunk

Let us know the impact on your fuel bill.