Oil Boiler short Cycling

GeorgeofLydda

Let me just start off by thanking everyone who contributes to this forum. Helps people like me greatly. I am a new homeowner and still new to the heating world.

We have been in our first home for a little over a year. We recently had our old boiler replaced for a new Weil-McLain WGO-4 boiler. It has a Beckett GenySys burner system.It is a 1955 home with original radiant floor heating in the concrete floors.This is the first cold snap we have dealt with and I can't tell if what we are experiencing is normal.

For starters we have gone through about a half a tank (275 Gallons) since the new year. Our house doe need a lot of work in the efficiency area. Using the My Technician app, I can see the boiler usually runs for about 5-10 minutes and then is off for 5-15 minutes. There are some exceptions where it ran for over 30 minutes and the occasional off time of over 30 minutes as well.

When it was installed the water temp was in the 180 degree range on the controller. The floors seemed excessively hot and the pipes made noise when warming up. For fear of damaging something I lowered the water temp down to 120ish. Early in the PA winter, we got about two months out of our tank. Not sure if that's normal either with the mild winter we had but it didn't seem crazy to me. I am just wondering if someone can help walk me through the goals of optimizing for efficient. Money is tight and oil is expensive. The house is currently set to 68 on the only thermostat and its just a standard Honeywell that was installed with the new Boiler. If I left out important information let me know. Thank you

pecmsg

How was the replacement sized?

5 - 10 minuets run time is barely enough to stabilize the boiler.

I see a seriously oversized boiler. Consider getting a buffer tank.

GeorgeofLydda

I believe it was sized based off the last boiler which was also a Weil-McLain. I don't remember if the previous boiler had the same issue.

Jamie Hall

How is the circulating water temperature controlled? You were quite correct to lower it to 120, although whether that will transfer enough heat into the floor to keep the house warm is another, not related, question.

Ideally the circulating water would be taken from the outlet of a mixing valve which took the cold inlet from the return from the floor, and the hot inlet from a T off a primary loop which went to the boiler. The rest of the return flow from the floor would be returned to the same primary loop. What this accomplishes is that the pump for the floor, which is taking water from the outlet of the mixing valve, can run all the time, sending "right temperature" water to the floor -- the "right temperature" being set by the mixing valve. The boiler then is controlled by the temperatures in the primary loop and only runs when more heat is needed. to keep the floor loop at the set temperature.

If the boiler is much too big and cycles on and off too often, you can add a buffer tank to the system, which stores hot water from the boiler and allows the boiler to run longer, but less often.

pecmsg

GeorgeofLydda said:

I believe it was sized based off the last boiler which was also a Weil-McLain. I don't remember if the previous boiler had the same issue.

Get a load calculation don on the structure and compare to the boiler in there. That will determine how to precede.

I'll bet your 50% oversized,

KC_Jones

pecmsg said:

GeorgeofLydda said:

I believe it was sized based off the last boiler which was also a Weil-McLain. I don't remember if the previous boiler had the same issue.

Get a load calculation don on the structure and compare to the boiler in there. That will determine how to precede.

I'll bet your 50% oversized,

This.

Even though it absolutely isn't done this way, let's get a shoot from the hip idea of how oversized you might be.

How many square feet is this house?

GeorgeofLydda

House is 1400 Sq Ft, single story with basement. Basement is not heated with the same system.

EdTheHeaterMan

I am going to make a guess that you have this piping setup.

That is because I also had a customer with copper pipe in a concrete slab heating system in a home that was also built in the 1950s.

This is not the best way to connect a cast iron boiler to a low temperature system. This is the way it was done in the 1950s because Mr Levitt Famous for his mass production assembly line construction technique in the developments that bare his name Levittown NY and Levittown PA. It was a failed low cost experiment. Failed because most heating radiator systems last for over 100 years in homes they are installed in, while within 20 years the copper pipes in the Levitt homes started to fail and today over 90% of those homes have abandoned those copper pipe systems in the floor. Successful in all other aspects because it was a low cost and efficient way to heat those homes.

Back to your system: The low temperature water needed to use that system 90° to 120° F will not play nice with a cast iron heater. To keep the flue gas from condensing in your Weil McLain boiler, the return water needs to be 140° or higher. Otherwise the flue gasses that are leaving the boiler will not get hot enough to burn off that condensation. We all know that condensation is actually water that is released from the air (the combustion gasses are loaded with water vapor) when they hit a surface with a temperature that is lower than the dew point of that air. In your boiler that temperature is over 130° but the 110 or lower return water temperature from the slab will cool that flue gas enough to condense that water vapor.

No big deal, Right? It's only water! Actually that water has trace elements of other byproducts of combustion from the sulfur in the fuel (even low sulfur fuel has some sulfur) and Carbon in the fuel (after all it is a HydroCarbon). And those trace elements can form sulfuric acid and carbonic acid that will literally rot the metal in the boiler away so you will need to replace it in 15 to 20 years from now. (I have worked on many Weil McLain Boilers that are over 50 years old)

So you may want to have that system redesigned by someone that understands Radiant floor heating and near boiler piping designs.

GeorgeofLydda

Jamie Hall said:

How is the circulating water temperature controlled? You were quite correct to lower it to 120, although whether that will transfer enough heat into the floor to keep the house warm is another, not related, question.

Ideally the circulating water would be taken from the outlet of a mixing valve which took the cold inlet from the return from the floor, and the hot inlet from a T off a primary loop which went to the boiler. The rest of the return flow from the floor would be returned to the same primary loop. What this accomplishes is that the pump for the floor, which is taking water from the outlet of the mixing valve, can run all the time, sending "right temperature" water to the floor -- the "right temperature" being set by the mixing valve. The boiler then is controlled by the temperatures in the primary loop and only runs when more heat is needed. to keep the floor loop at the set temperature.

If the boiler is much too big and cycles on and off too often, you can add a buffer tank to the system, which stores hot water from the boiler and allows the boiler to run longer, but less often.

I am not 100% on all of the industry terms so forgive me if I don't know what certain things are called. I work on the electrical side of things. The piping more or less was a direct replacement of what was installed before. From what I understand its just an in and and out with a fill line. I attached a picture in case that helps.

KC_Jones

You needed the smallest oil boiler made, and even that would have probably been too much.

And you have a different system for the basement, not connected to that boiler?

The WGO-4 has heating capacity between 122k and 146k depending on the burner settings. That equates to 88-105 btu's per sq ft. My 100+ year old hose with original windows and minimal insulation is ~38 btu's per sq ft. I'd be shocked if your 1955 build is more than 25-30, possibly lower.

As I said above, you needed the smallest boiler made in that line and it would have probably been way oversized too. A buffer tank might help, but that might not even be enough.

Also, you have radiant floors. Is there a mixing valve on them to temper the water temperature? You really shouldn't run an oil boiler at 120 all the time. It should be run higher with a mixing valve feeding the floor, as you experienced already the floor will get to hot.

It sounds like the company that did the work doesn't know what they are doing, and getting it resolved now may be difficult.

GeorgeofLydda

EdTheHeaterMan said:

I am going to make a guess that you have this piping setup.

That is because I also had a customer with copper pipe in a concrete slab heating system in a home that was also built in the 1950s.

This is not the best way to connect a cast iron boiler to a low temperature system. This is the way it was done in the 1950s because Mr Levitt Famous for his mass production assembly line construction technique in the developments that bare his name Levittown NY and Levittown PA. It was a failed low cost experiment. Failed because most heating radiator systems last for over 100 years in homes they are installed in, while within 20 years the copper pipes in the Levitt homes started to fail and today over 90% of those homes have abandoned those copper pipe systems in the floor. Successful in all other aspects because it was a low cost and efficient way to heat those homes.

Back to your system: The low temperature water needed to use that system 90° to 120° F will not play nice with a cast iron heater. To keep the flue gas from condensing in your Weil McLain boiler, the return water needs to be 140° or higher. Otherwise the flue gasses that are leaving the boiler will not get hot enough to burn off that condensation. We all know that condensation is actually water that is released from the air (the combustion gasses are loaded with water vapor) when they hit a surface with a temperature that is lower than the dew point of that air. In your boiler that temperature is over 130° but the 110 or lower return water temperature from the slab will cool that flue gas enough to condense that water vapor.

No big deal, Right? It's only water! Actually that water has trace elements of other byproducts of combustion from the sulfur in the fuel (even low sulfur fuel has some sulfur) and Carbon in the fuel (after all it is a HydroCarbon). And those trace elements can form sulfuric acid and carbonic acid that will literally rot the metal in the boiler away so you will need to replace it in 15 to 20 years from now. (I have worked on many Weil McLain Boilers that are over 50 years old)

So you may want to have that system redesigned by someone that understands Radiant floor heating and near boiler piping designs.

Pretty spot on. I guess I need to find someone in my area that can do that. Assuming the system is redesigned properly, will this boiler work for our needs? Or did we spend way too much money on something that is going to be useless for us?

EdTheHeaterMan

There is more: The 1955 copper pipe in a concrete slab may have just failed when you put very HOT water through those pipes for the first time in over 70 years. That caused the pipes to expand further than they have ever expanded before. That may have caused a stress leak in one or more of those copper pipes in the slab. If you are heating lots of water and putting that water into the ground under the slab, then replacing that water the leaked out with fresh water from the feeder valve, well you have just created an open system that will introduce fresh water into your (what was a closed system) boiler and accelerate the corrosion percess from the inside of the cast iron sections.

Condensation of flue gas on the outside and fresh water on the inside, You boiler may be toast in less than 10 years. If you can afford to pay for all that energy that is leaking into the ground. Every BTU of heated water that leaves the system thru a leak is a BTU that is lost forever never to return. But the ground below your home will be somewhat warmer. That may be where the tank of oil went in the last two weeks.

You are going to need to test the pipes for leaks. Shut off the heat and let everything cool down. Turn off the feed valve so no water goes into the boiler. Put air pressure in the boiler system up to about 20 PSI and see how long the pressure holds. It should hold for at least 5 hours without dripping much lower than say 18 PSI. I believe you are going to find that the pressure will drop to below 10 PSI within the hour, indicating that there is a leak in the system.

Now it is time to get new baseboard radiators installed throughout your home and abandon the slab heat as so many others have done.

Sorry to be the bearer of bad news, but this is the world we live in. Do you have a case to file against the boiler installer? Maybe. If he is insured you may win an insurance claim against his insurance company that will pay for the new radiators throughout your home. You need to prove that his negligence in letting that high temperature water into your pipes was the direct cause of the failure. May be easy to prove or it may not. I’m not a lawyer, I just know what happens in the heating system. You will need an expert witness that can make the lawyers and adjusters for the insurance company believe they will lose in court. Then the insurance company will write a check.

GeorgeofLydda

KC_Jones said:

You needed the smallest oil boiler made, and even that would have probably been too much.

And you have a different system for the basement, not connected to that boiler?

The WGO-4 has heating capacity between 122k and 146k depending on the burner settings. That equates to 88-105 btu's per sq ft. My 100+ year old hose with original windows and minimal insulation is ~38 btu's per sq ft. I'd be shocked if your 1955 build is more than 25-30, possibly lower.

As I said above, you needed the smallest boiler made in that line and it would have probably been way oversized too. A buffer tank might help, but that might not even be enough.

Also, you have radiant floors. Is there a mixing valve on them to temper the water temperature? You really shouldn't run an oil boiler at 120 all the time. It should be run higher with a mixing valve feeding the floor, as you experienced already the floor will get to hot.

It sounds like the company that did the work doesn't know what they are doing, and getting it resolved now may be difficult.

Not saying it isnt oversized, because it very well might be. Just adding in that our upstairs is mostly windows. Our living room has two walls consisting of almost entirely windows. It is a mid century house. The basement was finished after the original build. It just has some electric floorboard heaters.

EdTheHeaterMan

the Weil McLain boiler is still good. You can use it with the new baseboard radiators. it may be way oversized but it is still good. Perhaps the fact that the boiler has a greater capacity than you need and was set to a temperature that caused your pipes in the concrete slab to fail will win you a new boiler and baseboard heating system all in one. If you can't afford to heat the home because the fuel is being wasted into the failed slab heat, you may also get the insurance company to foot the bill for a hotel while the place is being fitted with a new working heating system. That usually gets the homeowners insurance people to start the new boiler system sooner than later if they are paying for lodging.

pecmsg

GeorgeofLydda said:

EdTheHeaterMan said:

I am going to make a guess that you have this piping setup.

That is because I also had a customer with copper pipe in a concrete slab heating system in a home that was also built in the 1950s.

This is not the best way to connect a cast iron boiler to a low temperature system. This is the way it was done in the 1950s because Mr Levitt Famous for his mass production assembly line construction technique in the developments that bare his name Levittown NY and Levittown PA. It was a failed low cost experiment. Failed because most heating radiator systems last for over 100 years in homes they are installed in, while within 20 years the copper pipes in the Levitt homes started to fail and today over 90% of those homes have abandoned those copper pipe systems in the floor. Successful in all other aspects because it was a low cost and efficient way to heat those homes.

Back to your system: The low temperature water needed to use that system 90° to 120° F will not play nice with a cast iron heater. To keep the flue gas from condensing in your Weil McLain boiler, the return water needs to be 140° or higher. Otherwise the flue gasses that are leaving the boiler will not get hot enough to burn off that condensation. We all know that condensation is actually water that is released from the air (the combustion gasses are loaded with water vapor) when they hit a surface with a temperature that is lower than the dew point of that air. In your boiler that temperature is over 130° but the 110 or lower return water temperature from the slab will cool that flue gas enough to condense that water vapor.

No big deal, Right? It's only water! Actually that water has trace elements of other byproducts of combustion from the sulfur in the fuel (even low sulfur fuel has some sulfur) and Carbon in the fuel (after all it is a HydroCarbon). And those trace elements can form sulfuric acid and carbonic acid that will literally rot the metal in the boiler away so you will need to replace it in 15 to 20 years from now. (I have worked on many Weil McLain Boilers that are over 50 years old)

So you may want to have that system redesigned by someone that understands Radiant floor heating and near boiler piping designs.

Pretty spot on. I guess I need to find someone in my area that can do that. Assuming the system is redesigned properly, will this boiler work for our needs? Or did we spend way too much money on something that is going to be useless for us?

Unable to tell at this time. As said get a heat load / loss performed and see how much extra there is. You can use some of the extra for your hot water needs. A buffer tank can be installed to give the system longer run / off times.
It all comes down to what's there and what's needed.

Choose the contractor wisely.
Post what they say here.

Where is this home located?

GeorgeofLydda

EdTheHeaterMan said:

There is more: The 1955 copper pipe in a concrete slab may have just failed when you put very HOT water through those pipes for the first time in over 70 years. That caused the pipes to expand further than they have ever expanded before. That may have caused a stress leak in one or more of those copper pipes in the slab. If you are heating lots of water and putting that water into the ground under the slab, then replacing that water the leaked out with fresh water from the feeder valve, well you have just created an open system that will introduce fresh water into your (what was a closed system) boiler and accelerate the corrosion percess from the inside of the cast iron sections.

Condensation of flue gas on the outside and fresh water on the inside, You boiler may be toast in less than 10 years. If you can afford to pay for all that energy that is leaking into the ground. Every BTU of heated water that leaves the system thru a leak is a BTU that is lost forever never to return. But the ground below your home will be somewhat warmer. That may be where the tank of oil went in the last two weeks.

You are going to need to test the pipes for leaks. Shut off the heat and let everything cool down. Turn off the feed valve so no water goes into the boiler. Put air pressure in the boiler system up to about 20 PSI and see how long the pressure holds. It should hold for at least 5 hours without dripping much lower than say 18 PSI. I believe you are going to find that the pressure will drop to below 10 PSI within the hour, indicating that there is a leak in the system.

Now it is time to get new baseboard radiators installed throughout your home and abandon the slab heat as so many others have done.

Sorry to be the bearer of bad news, but this is the world we live in. Do you have a case to file against the boiler installer? Maybe. If he is insured you may win an insurance claim against his insurance company that will pay for the new radiators throughout your home. You need to prove that his negligence in letting that high temperature water into your pipes was the direct cause of the failure. May be easy to prove or it may not. I’m not a lawyer, I just know what happens in the heating system. You will need an expert witness that can make the lawyers and adjusters for the insurance company believe they will lose in court. Then the insurance company will write a check.

I really appreciate the information. I thought really hard about abandoning the radiant floor before replacing the boiler but we love the floor heat and took the risk. Is it possible to test if the pipes have failed by closing off the fill line valves and just monitoring the system pressure? Don't to do more damage to anything.

GeorgeofLydda

pecmsg said:

GeorgeofLydda said:

EdTheHeaterMan said:

I am going to make a guess that you have this piping setup.

That is because I also had a customer with copper pipe in a concrete slab heating system in a home that was also built in the 1950s.

This is not the best way to connect a cast iron boiler to a low temperature system. This is the way it was done in the 1950s because Mr Levitt Famous for his mass production assembly line construction technique in the developments that bare his name Levittown NY and Levittown PA. It was a failed low cost experiment. Failed because most heating radiator systems last for over 100 years in homes they are installed in, while within 20 years the copper pipes in the Levitt homes started to fail and today over 90% of those homes have abandoned those copper pipe systems in the floor. Successful in all other aspects because it was a low cost and efficient way to heat those homes.

Back to your system: The low temperature water needed to use that system 90° to 120° F will not play nice with a cast iron heater. To keep the flue gas from condensing in your Weil McLain boiler, the return water needs to be 140° or higher. Otherwise the flue gasses that are leaving the boiler will not get hot enough to burn off that condensation. We all know that condensation is actually water that is released from the air (the combustion gasses are loaded with water vapor) when they hit a surface with a temperature that is lower than the dew point of that air. In your boiler that temperature is over 130° but the 110 or lower return water temperature from the slab will cool that flue gas enough to condense that water vapor.

No big deal, Right? It's only water! Actually that water has trace elements of other byproducts of combustion from the sulfur in the fuel (even low sulfur fuel has some sulfur) and Carbon in the fuel (after all it is a HydroCarbon). And those trace elements can form sulfuric acid and carbonic acid that will literally rot the metal in the boiler away so you will need to replace it in 15 to 20 years from now. (I have worked on many Weil McLain Boilers that are over 50 years old)

So you may want to have that system redesigned by someone that understands Radiant floor heating and near boiler piping designs.

Pretty spot on. I guess I need to find someone in my area that can do that. Assuming the system is redesigned properly, will this boiler work for our needs? Or did we spend way too much money on something that is going to be useless for us?

Unable to tell at this time. As said get a heat load / loss performed and see how much extra there is. You can use some of the extra for your hot water needs. A buffer tank can be installed to give the system longer run / off times.
It all comes down to what's there and what's needed.

Choose the contractor wisely.
Post what they say here.

Where is this home located?

We are in Southern Pennsylvania. Not too cold usually but the past few days have been.

GeorgeofLydda

Unfortunately the company that did the work is a family friend. It was officially done through the company, wasn't an under the table thing, but definitely would love to avoid the legal route. Definitely have a mess on my hands.

EdTheHeaterMan

GeorgeofLydda said:

I really appreciate the information. I thought really hard about abandoning the radiant floor before replacing the boiler but we love the floor heat and took the risk. Is it possible to test if the pipes have failed by closing off the fill line valves and just monitoring the system pressure? Don't to do more damage to anything.

YES. you will want the water too cool down for about 5 hours, then you will shut off the fill valve. then you will get a compressor and add air pressure to the system to 20 PSI. You don't want to use water pressure because the cold water will change temperature during the test. You want at least 20 PSI in the system to cause the the water in the slab to leak out of any small openings that may close up when they are colder.

This is the test I did for the customer I had, before I agreed to install the new boiler and connected to the copper pipes in his slab. The boiler was not leaking so I was able to do the test with the old boiler in place before removing it. The pressure started at 20 PSI and held, the next morning is was 21 PSI. If your test indicated you do not have a leak, then I will offer you the "best practice" near boiler piping diagram for you slab heating. Test the Slab First!

STEVEusaPA

Do you also use your boiler for domestic hot water?
What’s your zip code?
And tell me your usage between 2 fill ups, like this…
“ They filled my tank on Some date, then filled it again on another date and it took xxx amount of gallons”.

GeorgeofLydda

Thank you. I will test the slab and look in to getting a load calculation done. If only I would have known to start here before this. Thank you gentlemen. Really appreciate your willingness to share your knowledge.

KC_Jones

GeorgeofLydda said:

KC_Jones said:

You needed the smallest oil boiler made, and even that would have probably been too much.

And you have a different system for the basement, not connected to that boiler?

The WGO-4 has heating capacity between 122k and 146k depending on the burner settings. That equates to 88-105 btu's per sq ft. My 100+ year old hose with original windows and minimal insulation is ~38 btu's per sq ft. I'd be shocked if your 1955 build is more than 25-30, possibly lower.

As I said above, you needed the smallest boiler made in that line and it would have probably been way oversized too. A buffer tank might help, but that might not even be enough.

Also, you have radiant floors. Is there a mixing valve on them to temper the water temperature? You really shouldn't run an oil boiler at 120 all the time. It should be run higher with a mixing valve feeding the floor, as you experienced already the floor will get to hot.

It sounds like the company that did the work doesn't know what they are doing, and getting it resolved now may be difficult.

Not saying it isnt oversized, because it very well might be. Just adding in that our upstairs is mostly windows. Our living room has two walls consisting of almost entirely windows. It is a mid century house. The basement was finished after the original build. It just has some electric floorboard heaters.

To be clear, that boiler has enough output you could probably open a lot of those windows and still heat that house. It's comically oversized unless you live at the north pole.

I live in South Central PA, I'm quite familiar with the climate.

Also, radiant floors are only capable of putting out so much, about 25 btu's per sq ft, so if you have already been heating the house I would suggest that as your absolute upper limit. Which would equate to a boiler with an output of 34,500, which on oil doesn't exist. Again, the smallest boiler made is what you needed and that would have been too big.

I don't know what part of southern pa you are in, but I do know just about every contractor will not do their job correctly and argue that "no one does it that way", well they are right no one does it. That's not evidence of what is right or wrong, just evidence of what people do.

I wouldn't do a heat loss on your home given how small it is, but I would also know you needed the smallest boiler made. Anyone who's been doing this for even a short period of time should know this.

What was there before should not have even been considered...at all.

STEVEusaPA

Do you also use your boiler for domestic hot water?
What’s your zip code?
And tell me your usage between 2 fill ups, like this…
“ They filled my tank on Some date, then filled it again on another date and it took x amount of gallons”.

GeorgeofLydda

STEVEusaPA said:

Do you also use your boiler for domestic hot water?
What’s your zip code?
And tell me your usage between 2 fill ups, like this…
“ They filled my tank on Some date, then filled it again on another date and it took x amount of gallons”.

No we currently have an electric water heater. It's about 27 years old so it will need replaced soon as well.

17339

Only have had two fill ups with this boiler and the first was a partial fill up to get ready for the winter. I don't have the dates on hand but from full, two months we used about 200 gallons when winter started. Roughly end of October to end of December. We filled up right around the near year, (credit card statement was 1/6 but it was filled a few days prior). Since then we have used about 137.5 gallons. (Tank gauge is just about half full).

GeorgeofLydda

As a side question, should the economy mode be on? Currently in the off position with the 0-5 being the other choices. May be a stupid question but oh well.

STEVEusaPA

You’re not giving me much to go on, but here’s a WAG…Basically the smallest boiler will still be too big. Maybe a buffer tank is in your future.

pecmsg

STEVEusaPA said:

You’re not giving me much to go on, but here’s a WAG…Basically the smallest boiler will still be too big. Maybe a buffer tank is in your future.

add in the Hot Water and that's the solution.

STEVEusaPA

pecmsg said:

add in the Hot Water and that's the solution.

Maybe even a reverse indirect. Although I’d probably put in an EK and let it dump into the storage tank.