Boiler conversion

Curtis572

Hello I have an old super hot ss360 boiler in my house and it is a single stage natural gas guzzler.  I was looking at replacing it with a high efficiency boiler but the cost of that is not quite in the books at the moment.  
For the mean time I was wondering if a unit like this could be converted to a multi stage unit via a controlled gas valve? Kinda like a natural gas BBQ. 
I was thinking if there was a controller monitoring the inlet and outlet temperatures which would than in turn open or close the gas control valve as needed. 
My thought behind this is that on milder days maybe it will consume much less gas? 
From my understanding condensing boilers work similar to this, I know they have a different heat exchanger than the boiler I have but I am curious if it will work and if so where a person would find a kit if there is such a thing or maybe if it is possible it would just have to be pieced together. 

Any feedback or insight on this would be greatly appreciated! 

Jamie Hall

In theory one could just vary the gas flow, like your barbeque. In practice... your efficiencies would drop like rocks at anything off where it was adjusted to. Not that it can't be done -- but not by simply adjusting gas flow pressure. Combustion air has to adjust too, and the burners have to be built to maintain good heat distribution in the firebox and heat exchangers.

gyrfalcon

@Curtis572, I have an old war tank of a boiler from the early 80s. 100k btu input for a house with under 2k sqft.  I’ve been reading this forum for a few years now and in no way am a pro. But I feel very confident in understanding my home’s boiler and emitter system, thanks to all of the wonderful people on heating help.com.  

As Jamie noted, it could be done ,in theory, but not realistically. To find someone with the absolute understanding of this type of modification would likely be very expensive for their design time, labor to install and specialized parts for a one off prototype.  New modulating boilers can adjust gas flow to match needed output using sophisticated control systems, variable gas valves, variable inducer fans, water circulators . Also the heat exchangers are made specifically for this task. . 

Our old dumb boat anchors are not made to do so, if we tried, it would not work out very well for our pocket books, home temperature and boiler would likely die quickly due to unfavorable conditions . 

WMno57

Mod-Cons are more efficient. For two reasons, Mod and Con. Let's talk about that.
Mod is Modulating. Another term for this is turndown or Down Firing. The idea is to run the boiler at the heat loss of the home which varies given outdoor temp (and wind on my drafty old house). Many discussions here on down firing boilers. Not as easy to do as it sounds. One of the bigger problems with down firing is condensation. Condensation is Acid and will destroy the boiler and chimney in a very short time. You might be able to down fire your boiler 10 percent IF YOU HAVE AN EXPENSIVE DIGITAL COMBUSTION ANALYZER TO VERIFY YOU ARE NOT CONDENSING. That doesn't mean you will save 10 percent on your gas bill. Your boiler modulates now by turning on and off. Modulating is over rated. Just size a non modulating boiler correctly to start with. Remember sizing when you buy your new boiler.
Con is Condensing. The idea is to extract another 10 percent of the energy from the fire before sending the exhaust out of the home. Mod Cons are built with materials that can tolerate acidic condensate. Sort of. They still wear out a lot sooner than my non Mod or Con 75 year old cast iron boiler.
That is why no one makes a kit. Making your own would not save you much, and would destroy something with acidic condensate.

Curtis572

Thank you everyone. I tried searching for some information on this within this site and across the web but could not find anything. Perhaps I did not have the proper search terms. 

Basically I need to just deal with the gas consumption until I go for a newer boiler. I am glad this one is very simple and seems to work well, it just sucks back the gas way too fast but it is what it is.  

I guess the next question would be is does anyone have any feed back on what is a better boiler to go for? From my understanding on my last post there is a higher efficiency cast iron boiler that lasts longer than the high efficiency units but not as efficient as those ones.  

I am just wondering if the cast iron ones with a longer life but higher gas consumption is more cost efficient than the highest efficiency boilers that fail earlier. 

Any feed back on this would be much appreciated! I'll have to read through the posts more on this site to get more information 

gyrfalcon

As inefficient or gas thirsty as your boiler seems, where is all of the heat going that it has made? 

The goal is for the to be in your house and keep it there.  My boiler in big and “inefficient” too but my house also needs to be tightened up some more.  If your house cannot keep the heat,  a more efficient boiler may not necessarily reduce your fuel consumption. 

 You need a heat loss calculation , emitter / radiation survey, maybe air infiltration/ blower door test before deciding what to do.  

retiredguy

I have no idea what boiler you have but if you feel that your heating bills are excessive try reducing the buildings heat loss. Make sure that you have energy efficient windows and doors, good wall insulation, R-30 or better attic insulation, and have reduced all air infiltration. This will be the best money spent. Gaining a little increase on the boiler's efficiency should be the last money spent, in my opinion.

Steamhead

gyrfalcon said:

As inefficient or gas thirsty as your boiler seems, where is all of the heat going that it has made? 

The goal is for the to be in your house and keep it there.  My boiler in big and “inefficient” too but my house also needs to be tightened up some more.  If your house cannot keep the heat,  a more efficient boiler may not necessarily reduce your fuel consumption. 

 You need a heat loss calculation , emitter / radiation survey, maybe air infiltration/ blower door test before deciding what to do.  

retiredguy said:

I have no idea what boiler you have but if you feel that your heating bills are excessive try reducing the buildings heat loss. Make sure that you have energy efficient windows and doors, good wall insulation, R-30 or better attic insulation, and have reduced all air infiltration. This will be the best money spent. Gaining a little increase on the boiler's efficiency should be the last money spent, in my opinion.

This!

hot_rod

You might look into having a blower door test done. this will show where all the air leaks are. Some will be easy and cost effective to seal up. weatherstripping for example.

Then a second blower door test after any upgrades, using that number for infiltration in the heatloss calculation.

Some energy audit companies can do all this for you, blower door test and load calc for heat and cooling.

Then I would look at the type and quantity of heat emitters. See how low of a temperature you could run in the system.

If you can run SWT below 140 for some or all of the year, the mod con boilers, by numerous owner reports on here, can save 30%.

If you have combustion air vents into the boiler room now, those can be sealed off with a mod con installation also. Keep the snow from blowing inside you home

So the answer is very specific to your home and application. Many experience increased comfort with mod con boilers also, as you can get close to constant circulation, hardly any on/ off cycling of the boiler. Heat input is always at the ideal amount for the load.

15- 20 years is a reasonable life expectancy for a quality, properly installed and maintained mod con.

Curtis572

Thanks again for all of the responses, I did have the blower door test done I should look for those results. I replaced all the windows in the house because they were original to the home when I moved in and all wood frames, half of them didn't even seal so that was a huge upgrade. 

I'll have to crawl into my attic and see how the insulation is doing up there. I also do have a thermal imaging gun I could walk around the exterior of the house when it's cold out and see where all the heat's coming out of. I keep  getting wrapped up with all the other projects on hand I keep forgetting about just doing a simple walk around with the imaging gun. 

Greatly appreciate the input everyone! Just have to keep it simple and keep the heat in, it makes alot of sense. The less the boiler need to run the better. 

I renovated a large room and I know that's fairly well sealed up but it is a 1980 home and I'm not sure about the rest of the house. I'll have to find some hot spots from outside and cold spots inside and improve insulation/sealing it up better in those areas.