Indoor temperature constant, but gas boiler keeps firing up

JimHP

My wife knows quite a bit, but I am 100% new to gas boilers and radiator heat, So these questions might be simple or easily answered or not explained enough. Sorry for that. If there is a better place to ask or get answers please direct me to the appropriate place.

We have a wired thermostat. I check it all the time and the target temp and actual temp are always the same until evening/night. Even so, our gas boiler still comes on constantly. This is not making any sense to me. If the target temp is reached and actual temp never lowers, why is the system continually firing up the boiler? Is the system that exacting or is something broken? I am used to forced air, where the system rests until the temp drops below the target.
We are also concerned we might need a more efficient boiler. Our gas bills are quite a lot higher than we were told they would be. Our boiler is about 20 years old, and has been checked and OK-ed by an HVAC professional as fully operational. Would a more efficient boiler run less often, thereby using less gas? Or is it not that simple?
We have also been told a new boiler comes with the recommendation of new radiators (ours are 50+ years old, and they all work). Is this necessary because of the increased efficiency of the newer boiler, or is it just a sales technique?
Our piping in the basement is asbestos-wrapped, but it is pretty old and shredded in many places. Are we possibly losing so much of the heat to the basement - it is always warm down there, which I know is normal for this type of system - because of the poorly wrapped pipes?
OK, this turned into many questions, but any help I can get is appreciated. I will do my best to get any data or info requested. Please try to keep it basic enough for me if possible.

Thanks,
-Jim

JUGHNE

Pictures of t-stat, boiler piping, controls, boiler gauge and the typical radiator.

pecmsg

If you're at or near design conditions, then the boiler should run continuously. If it is cycling on and off
1) a safety is shutting it down
or
2) It's seriously oversized.

From here with the limited information sounds like its oversized. That boiler needs 10 - 15 mins run time to stabilize, short cycling is never good.

ratio

Is the stat digital? Some models will show the 'room temp' as unchanging unless it drops significantly below the setting.

As for upgrading, it's almost certainly going to be cheaper in the short, medium, & kinda-long term to make (correct) repairs than change to something (anything) else. ROI will be in the decades range. The first step to replacement is a Manual J heat loss. If anyone offers to size a new system by what's currently there, smile & gently show them to the door.

JUGHNE

Or if they try to sell you new radiators, assuming yours do not leak.
Pictures?

JimHP

Pics are attached, more can be provided if needed.
The house is 2100 sq. ft.

JimHP

Pics.

pecmsg

Be very very careful with that insulation.

Can you take pics of the boiler piping from about 10' away?

JimHP

Thanks. We know the pipes need re-wrapping, and we aren't actively touching them.
Our radiators are old, but we know they all work just fine since they all get quite warm. We had new release vents put on a few of them.
Our thermostat is wired, on the first floor, towards the front of the house, which faces south, which is to our advantage since it warms the area of the t-stat. Some rooms of the house are colder, but we are OK with that (room is either at the end of the pipe run, probably; and/or the room is uninsulated, and not near the t-stat).
If replacing/upgrading the boiler is unlikely to address the issue(s), what measures can be taken instead?

EBEBRATT-Ed

@JimHP

We will try and help from here. If you need a contractor that knows something check "find a contractor" on this site and post your location. Someone may know someone they would recommend

pecmsg

I'm confident that's Asbestos insulation BUT, without actual tests we can't say. Assume it is until verified. Look for spray encapsulants.

JUGHNE

Picture of the grey Honeywell box to the upper left of the pressure gauge.
Include the gauge and the curly pipe "pigtail" connection.
'
Picture of the nameplate of the boiler....Input---buth etc.

Look for main vents at the end of the steam main pipes, pictures of them.
They will look like a large version of the ones on the radiators.

Plan to have that asbestos insulation professionally removed and replaced with fiberglass insulation....did you just buy this house?

A new boiler would be maybe 1-2% more efficient than what you have.
There is little other choice for radiators for steam, unless you want to spend plenty.

Does your tstat show when it is calling for heat? Picture?

pecmsg

JUGHNE said:

Picture of the grey Honeywell box to the upper left of the pressure gauge.
Include the gauge and the curly pipe "pigtail" connection.
'
Picture of the nameplate of the boiler....Input---buth etc.

Look for main vents at the end of the steam main pipes, pictures of them.
They will look like a large version of the ones on the radiators.

Plan to have that asbestos insulation professionally removed and replaced with fiberglass insulation....did you just buy this house?

A new boiler would be maybe 1-2% more efficient than what you have.
There is little other choice for radiators for steam, unless you want to spend plenty.

Does your tstat show when it is calling for heat? Picture?

Where is this house located?

JimHP

We live in Highland Park, MI. House is 110 years old. The radiators might be original, but the boiler, luckily, is not.
T-stat is super-basic, shows nothing (pic included).
We are unlikely to get the asbestos covering remediated and replaced any time soon. We don't have the money for that and it isn't dangerous as long as we are leaving it alone. Yes, it would be best to take it out, obviously.

Jamie Hall

Let me go back your initial question, @JimHP . The boiler will need to fire up from time to time to keep the temperature in the building more or less constant, since the building is always losing heat and trying to cool off.

If your thermostat is managing to keep the temperature constant within a very narrow band, it is doing its job properly, and doing it well. As others have pointed out, most digital thermostats won't show a room temperature change of less than 1 degree -- they can't. So I wouldn't be misled. It's working fine.

Now -- someone suggested your radiators are 50 years old so they would have to be changed. Which is pure unadulterated baloney. I would not allow that contractor back into your house under any circumstances. He or she is either misinformed or a crook, and neither one is good.

Your boiler is older, and sooner or later it will wear out or fail. Machines do. At that time you will need to replace it, and it is quite likely that a new boiler will be more efficient. How much more efficient? Hard to say -- if your existing boiler has been well maintained you might gain 10%, but it's unlikely that you will gain more. What you have isn't that old.

And, by extension, 10% is the most you could expect to save on fuel -- which won't pay for a new boiler. I'm not that surprised to hear that you are using more fuel than you were led to believe would be the case, however -- it's a rare seller, never mind real estate person, who will be able to give a truly honest answer as to how much fuel they used. People always underestimate even without meaning to, unless they have kept more than usually accurate records.

The best place to put money is in insulating those steam pipes -- and even more into making sure that your house is reasonably draught tight (good doors, good storm windows (don't fall for replacement windows, unless yours are really horrible), more structural insulation.

JimHP

We have a contractor we trust, and the system has been checked completely. All the radiators get hot, the wider ones stay cold at the end furthest from the pipe connection, but I have been told that is normal.
We are considering a 2-zone system at some later date, maybe, but that's unimportant until we figure out what our current system is doing that is causing such high gas use. If a new boiler would only provide 1-2% efficiency gain, something else is the cause, or at least a new boiler isn't going to help us.
We know insulation in our crawlspace and walls for the house addition (1st and 2nd floor) at the north/back side of the house will make those rooms warmer. But the areas of the house around the t-stat are warm and their radiators are working just fine.
What we are trying to figure out is why our system seems to come on so often when the temp of the house is not going down to warrant this. Which could be how the system operates, and we just have to deal with super-high gas bills in the winter months.

JimHP

Our contractor never suggested we need to replace the rads, that was me reading off the internet about what getting a new boiler would recommend and putting it in my post. Sorry if that was unclear.

JUGHNE

What is the AFUE efficiency on the yellow tag on your boiler?

Your tstat shows a call for heat with the small flame symbol in the lower right hand corner.

If you turn the temp down by 3-4 degrees the flame should go away and the boiler should stop firing. You should check that out.

I looks like your pigtail may have been cleaned recently as evidenced by the fresh blue tape applied to the threads for re-assembly.

And then how about main vents?

Jamie Hall

One thing which you need to factor in to your "super high gas bills". Don't compare dollar amounts. Compare therms or cubic feet. As I am sure you are aware, natural gas prices have risen substantially over the last 6 to 9 months, and I hate to say this but they are only going to get higher...

JUGHNE

JimHP said:

replace the rads, that was me reading off the internet about what getting a new boiler

We should probably not allow the internet into our house either.... ...really.

PC7060

Agree 100% with what Jamie Hall said:

Now -- someone suggested your radiators are 50 years old so they would have to be changed. Which is pure unadulterated baloney.

wmgeorge

I'd check the cycle time on your T'stat most digitals are set to cycle 4 times an hour. NG prices have shot way high, go by Therms used instead of cost.