Boiler start/warm up time

Ryan78

I recently bought a house with an oil boiler and radiators and im trying to get the rooms balanced a little better. The house is 1500sq ft and was built in 1961 and had a first floor addition added at some point. The boiler is a Burnham V83 [installed in 2010] with a Honeywell Ct87K stat, L7224U aquastat and taco 007 circ. It is for Heat only since i have electric hot water heater. It is a single zone but splits off at boiler along north and south sides of the house. So both sides have a suply and a return. It's has cast iron piping except for the addition which is copper. Three rooms have cast iron base board and the rest have CI radiators (6).
When there is a call for Heat both the burner and circ come on. Today while monitoring the boiler on start up I noticed that once the circ kicked on the temp dropped pretty rapid . Once it got down to 140 the circ stopped but the temp continued to drop to 120. A few minutes later with temp was back up to 160 and the circulator kicked on again. This cycle continued until the tstat was satisfied. Is that normal? The settings on the aquastat are
HL- 180 HLdif - 15
LL-160 LLdif - 20
The second floor was getting way to hot so I turned the valves in to the point where they are almost closed and that seemed to help. My concern with that though is having pipes freeze in the wall. Its a brick house without wall insulation. The addition which is furthest away from boiler still stays anywhere from 2 - 5 degrees colder than the rest of the house. Im not sure if those walls have insulation.

EBEBRATT-Ed

Best thing would be to post some pictures of the boiler and heating system or a sketch of the piping. We would be glad to help.

As far as the boiler operation was their ever a tankless coil in the boiler for DHW? Sounds like the aqustat you have is a model used for DHW

nicholas bonham-carter

If you are using temperature setbacks, that may be a problem in getting the eveness of heat you desire.
Leaving it a constant setting might be better.—NBC

Ryan78

I'm not sure if there was ever a tankless coil. The electric hot water heater was installed 3 years after the boiler was. Here is a picture of the piping coming out of the top of the boiler. I will take more pictures after work today.
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Ryan78

> @nicholas bonham-carter said:
> If you are using temperature setbacks, that may be a problem in getting the eveness of heat you desire.
> Leaving it a constant setting might be better.—NBC

I was using large setbacks at first but after a lot of reading on this site I realized that I probably wasn't saving any fuel. For the past two weeks I've been keeping the stat set at 68 degrees from the time I get home from work until I go to bed then I turn it down a little, 66-67. I haven't noticed much of a difference.

Ryan78

So I just went in the basement and took some more pictures. Also correction on the age of equipment. It looks like the boiler was manufactured in October of 2007 and the hot water tank in 2015. I don't know much about the history of the home because it was a foreclosure that's not empty for a couple years. I bought it in 2017 from an investor.

Ryan78

Another

Ryan78

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Ryan78

Aquastat and Flo control

HVACNUT

Looks like it's moving a lot of water. A bypass probably should have been piped in.
Is the 007 sufficient?
BTW, the circ says IFC. The check valve should've been removed if the existing Flo valve works.
You can turn down the low all the way and set the high to 180 and high diff to 30.
If your really into it, you can bring home runs from the 2nd floor rads back to the boiler and make it it's own zone. Wireless thermostat if you can't get a wire up to the 2nd floor.
Even though it's mono Flo, the installers should have knocked out that wye and piped in a couple ball valves and a purge drain.

Ryan78

> @HVACNUT said:
> Looks like it's moving a lot of water. A bypass probably should have been piped in.
> Is the 007 sufficient?
> BTW, the circ says IFC. The check valve should've been removed if the existing Flo valve works.
> You can turn down the low all the way and set the high to 180 and high diff to 30.
> If your really into it, you can bring home runs from the 2nd floor rads back to the boiler and make it it's own zone. Wireless thermostat if you can't get a wire up to the 2nd floor.
> Even though it's mono Flo, the installers should have knocked out that wye and piped in a couple ball valves and a purge drain.

A bypass on the return?
I'm not really sure if the 007 is sufficient. I look up the specs and it said...max flow 17gpm and the max head is 8.5 ft. How do I figure out the head?
Thanks for pointing out that it's an IFC, I overlooked that. I'm not really sure if the existing flow valve works. If I turned it out counter clockwise would that disable it and let the check in the pump do it's thing?
I see what you are saying about the valves and purge drain. They certainly didn't install it as per Taco instructions.
I think seperating the upstairs onto its own zone will be a last resort.
I'll try changing aquastat to see if that helps.
Thanks for your knowledge and advice

Ryan78

I was abble to disable the low limit but it will only let met set the high diff to a max of 20. Since I couldn't set it to 30 as suggested, should i lower HL a little?

Ryan78

Well disabling the low probably not a good idea. Allows circ to continue to run during warm up and temp went from 155 to 101 before it started to rise up again. I set it to 140 diff @10. That kicks circ off at 130.

Reading through the Burnham install manual they dont list this aquastat (L7224U) for any configuration. It says on water boilers without tankless heater set the L8148 to 180 degrees. Maybe i should get the aquastat that the mfg. Recommends for my application? I'm guessing that control would make the circ function different than mine is now? Seems like the L7224U operates the circ off of low limit settings once there is a call for heat.

Zman

If closing the valves on the second floor fixes the overheating issues with no ill effects elsewhere, it sounds like it is on it's own parallel loop. You could add a zone valve with a thermostat (would need wire and power) or a thermostatic radiator valve (no wires needed) at that location to regulate temperatures.

As for the boiler, that is a really clunky way to maintain non condensing boiler temps. Installing a thermostatic mixing valve would be much better. https://www.youtube.com/watch?v=yfEyGy50P20

HVACNUT

> @Zman said:
> If closing the valves on the second floor fixes the overheating issues with no ill effects elsewhere, it sounds like it is on it's own parallel loop. You could add a zone valve with a thermostat (would need wire and power) or a thermostatic radiator valve (no wires needed) at that location to regulate temperatures.
>
> As for the boiler, that is a really clunky way to maintain non condensing boiler temps. Installing a thermostatic mixing valve would be much better.

It looks to be a monoflo loop, split north and south, not up and down.
The mixing valve make excellent sense.
@Ryan78, the L8148 is a cold start aquastat.

SeymourCates

Ryan78 said:

Well disabling the low probably not a good idea. Allows circ to continue to run during warm up and temp went from 155 to 101 before it started to rise up again. I set it to 140 diff @10. That kicks circ off at 130.



Reading through the Burnham install manual they dont list this aquastat (L7224U) for any configuration. It says on water boilers without tankless heater set the L8148 to 180 degrees. Maybe i should get the aquastat that the mfg. Recommends for my application? I'm guessing that control would make the circ function different than mine is now? Seems like the L7224U operates the circ off of low limit settings once there is a call for heat.

The 7224U is perfectly fine for your application. As you noted, you need the low limit if the system has reasonable mass and you wish to prevent the boiler temperature to rise above condensing temperature (128F for fuel oil) in a "reasonable time". Using the 7224U achieves that objective and shuts the circulator down when the boiler drops below low limit (minus the differential). Setting the Low limit to 140F with a diff of 10 is perfectly fine.

What is recommended to save on fuel is to reduce the high limit setting to 160F with the 20F differential, Be cognizant of the fact that it might not heat the building to the thermostat setting on the coldest days of the year. On those days, just push the setting up a bit.

The 7248 will not keep the boiler at the low limit setting. It will allow the boiler to go dead cold between calls and will save on fuel. HOWEVER, it will also start the circulators immediately on a heat call and the boiler must then bring both itself and the system up above condensing temperature simultaneously. Usually, the time is longer than desired,

Also note that this boiler will run the entire off season and maintain 140F for no good reason. It requires you to shut it down manually once the heating season is over.

Ryan78

> @HVACNUT said:
> > @Zman said:
> > If closing the valves on the second floor fixes the overheating issues with no ill effects elsewhere, it sounds like it is on it's own parallel loop. You could add a zone valve with a thermostat (would need wire and power) or a thermostatic radiator valve (no wires needed) at that location to regulate temperatures.
> >
> > As for the boiler, that is a really clunky way to maintain non condensing boiler temps. Installing a thermostatic mixing valve would be much better.
>
> It looks to be a monoflo loop, split north and south, not up and down.
> The mixing valve make excellent sense.
> @Ryan78, the L8148 is a cold start aquastat.
>
>

HVACNUT is correct about how the system is split. I definitely like the mixing valve idea, it seems that would also help out with efficiency. I might look into that a little further to see if it's something I could handle installing myself . I certainly wouldn't have money the moment to pay someone to do it . Since Burnham recommends a cold start aquastat for my configuration does that mean that it is a cold start boiler? I think that would make me a little nervous. I'm pretty sure I read in the past that this particular model has been known to have issues with cracking.

@SeymourCates- thank you for your input. what is considered a "reasonable time" for it to rise above condensing temperature?
Is it safe to manually shut the boiler down once heating season is over?

SeymourCates

@Ryan78

One would prefer if the boiler climbed above 130F within 10 minutes, However, it is more important for the boiler to continue to run for 10 minutes after 130F is achieved. That's difficult for most oil fired systems with low mass,

Yes, it is perfectly fine. Cold start aquastats do the exact same thing on a daily basis, You will get the counter argument for durability of the boiler. Ask if the counter argument is worth an estimated $200/year in additional fuel cost against the potential deterioration from six months of no operation,

Greenesoil

I would recommend you split the upstairs from the downstairs by adding a zone which will reduce the amount of cold water returning to the boiler when the circulator starts. What you have now is called a cold shock. By splitting the upstairs from the downstairs this will reduce the large amount of cold water causing the temp to cool down and this will also eliminate the over heating of the upstairs

Ryan78

If I was to split the upstairs to its own zone would that help to bring up the temperature of the two 1st floor rooms furthest from the Boiler? Those rooms generally are 5 degrees cooler then the other first-floor rooms which are first in line. Like I said the upstairs rooms are generally 5 degrees warmer then the first in line first floor rooms.

The weird thing is that those cast iron baseboards and get nice and warm in those rooms. I guess it could be a heat loss issue rather than a flow problem.

Zman

If all the radiators are getting hot and some rooms are overshooting, your radiation to heat loss ratio is out of balance from room to room. Zoning would take care of it as would radiator covers.