Best way to manage temperature swings? What's normal? need a new thermostat?

Jack M

What's the best way to keep an even temp in the house now that Spring has arrived? The temperature in the house are pretty consistent during the winter. With more moderate outside temp (30's) I notice that the boiler kicks on and runs until the thermostat's temperature is satisfied. The boiler shuts off however the residual heat in the radiators will carry the inside temp up 5 or 6 degrees over the thermostat setting. In the dead of winter this does not happen.
In the winter the radiator's residual heat makes up for any heat loss. (The room stays a consistent temp).
Is there a way to compensate for the temperature swings? Is there potentially a flaw in the steam system's design?
I could slow the radiator vents down if I needed to, I guess. I have an old circular Honeywell thermostat. Would a modern digital one give me better control of the fluxuations? The radiators are filling about 1/2 way across at the most before the thermostat shuts down.

KC_Jones

http://www.twotwelvef.com/uploads/3/4/2/8/3428833/twotwelvef_ecosteam_product_brochure.pdf

Jamie Hall

You may just need to adjust the anticipator setting of the thermostat.

ChrisJ

I second the EcoSteam.
It's the only thing that worked for me.

Mark N

What is the anticipator set to? How long does the boiler run? How long is it off in between calls for heat? Is the boiler oversized? Need more information. A properly set up Honeywell T87 should work great. I use a Honeywell FocusPro 5000 and have never experienced what you describe. I used to have a T87 and it worked just fine as long as the anticipator was set properly.

nicholas bonham-carter

In the shoulder seasons, the main venting becomes even more important for comfort. You want the air out of the system as quickly as possible so all the radiators get steam at the same time.
Time the steam arrival to the last radiator on each main from the point of the header being steam hot, and let us know how long that is.--NBC

ChrisJ

Mark N said:

What is the anticipator set to? How long does the boiler run? How long is it off in between calls for heat? Is the boiler oversized? Need more information. A properly set up Honeywell T87 should work great. I use a Honeywell FocusPro 5000 and have never experienced what you describe. I used to have a T87 and it worked just fine as long as the anticipator was set properly.

What CPH is your FocusPro 5000 set to?

I had a T87 for a short time that I ended up giving to Crash2009. If I set the anticipator to work well during a certain time of the year it worked awful other times.

Mark N

Chris it was set to 0.8 amp as per the burnham manual

ChrisJ

Mark N said:

Chris it was set to 0.8 amp as per the burnham manual

What's your FocusPro 5000 set to?

Mark N

1cph

ChrisJ

Mark N said:

1cph

Running 1 CPH you never see wide temperature fluctuations, even when it's in the single digits out?

Mark N

No it will maintain 70 quite nicely. It will run slightly longer and run more often.

ChrisJ

Mark N said:

No it will maintain 70 quite nicely. It will run slightly longer and run more often.

Then your system must have something special about it. I have a FocusPro 5000 on my neighbor's system and his sees quite large swings.

When it's in the teens out if I'm running only the VisionPro 8000 I'll see 2 degree swings as a minimum. When it's below 0 out I'll see as much as a 4 degree swing.

It's a bit hard to run approximately 1 cycle per hour and maintain a tight temperature swing when the house is loosing heat fast. Even set to 2 CPH mine has a hard time without the EcoSteam.

With the EcoSteam I can maintain very tight swings depending on a few things. If I get it just right the temperature won't change at all but typically, it varies within 0.5F.

Jamie Hall

Umm... well, I use a VisionPro on my system, and I see perhaps a 1 degree swing. Max. It's set to 1 cycle per hour. Used to have a T87 as the main thermostat (there are still two of them for backup and emergency control). Likewise -- about 1 degree swing.

My own feeling? It's more in the venting and sizing the system so it all works together. If those basics aren't really up to speed, all the fancy controls in the world aren't going to help.

Mark N

Chris, as per design the FocusPro is + or - 1 degree. I placed a digital thermostat that reads in 1/10 of a degree increments next to the thermostat and it will maintain a 1 degree differential. I've had no luck with a 2 cph setting. I can live with a 1 degree swing. The temp is very uniform throughout the house. One room may be at 69 and another at 71 according. I never see big temp swings. I never had a spitting or hissing air vent. Matter of fact I've never observed the rad vents ever closing. Both my mains are exactly the same length with near equal amounts of dads attached to them. Very easy to balance. I have thought of getting an EcoSteam but have t made up my mind.

Fred

We've had this discussion before, if my memory servves me right I second what Mark N and Jamie Hall say. I have a Honeywell 7000 series and I don't see more than a 1 degree variance at any time.

MarkS

Jamie Hall said:

My own feeling? It's more in the venting and sizing the system so it all works together. If those basics aren't really up to speed, all the fancy controls in the world aren't going to help.

Jamie is absolutely correct. The system must be in good running order before any sort of advanced control can be considered, be it EcoSteam or PMJs timed cycle control or Tekmar. That's the first question I ask of any prospective customer. I can envision scenarios where putting an advanced control on a poorly operating system can actually make things worse.

PMJ

My experience with my steam system is that it has the most trouble providing even heat when very little total heat is needed - the 45+ days of fall and spring. Most thermostats are usually in the center of the house and once satisfied it may be hours before another call comes. When it does come it takes almost no run time to satisfy again. These are just not good conditions for even heat with steam.

Any control which spreads out the firings will prevent overshoots at the thermostat and will help; and I agree that a good running system is always required. But fundamentally steam does less and less well when the total run time as a percent of elapsed time gets very low.

ChrisJ

I've been doing 30 minute cycles, though I did try 20 minute cycles for a bit.

20 minute cycles works great if its in the single digits or below zero out. It was actually quite interesting to watch as well because of the incredibly short preheat times and extremely steady indoor temperature when it was -2f outside.


I could do 3 cycles per hour normally, but the VisionPro gets into a weird habit of doing 2 short cycles followed by 1 long one or something like that. Once it warmed up into the 20s or 30s it threw off it's rhythm.

PMJ

Let's face it, these things really run best when you really need heat. That's a good thing - much better than the other way around anyway. I'm glad others have experienced that more cycles is ok when it is cold as there almost is no preheat time.

When it is warm out and you really don't need much heat you don't really have a cph rate as the whole thing may be off hours after being satisfied each time - especially if the sun comes out. At -5 deg I was probably doing 60+ cycles a day. At 50deg outside with the same program there may not be even 5 cycles. Under these circumstances I sometimes raise the setpoint a degree or 2 in April and skip the setback. When so little total heat is needed neither of those things makes much difference in cost anyway. There is no vacuum to take advantage of either at that point.

Jack M

What if you reduced the EDR? Could it help in these 50 degree days if a few radiators were shut off? The few that were available could be set to vent rapidly and the cycle could be shorter. The lower heat loss in the rooms would create less imbalance. You would not be shutting off on pressure.

ChrisJ

Reducing radiation and essentially making your boiler appear larger to areas is the complete opposite of what you want to do.

Think of it like this.
When do these systems really work the best? When it's really cold out. The colder it is, the better they work.

What you would want is your boiler smaller on more mild days to increase run times. If you're having issues with venting on mild days that should be corrected. If I only let my boiler run for 30 seconds after I first feel heat at one radiator, all 10 will be similar at the end of that 30 seconds. Two may be a little hotter, but that's intentional because those rooms have higher heatloss.

You can control everything your system does via venting and it can be done incredibly accurate.

@Hatterasguy
The EcoSteam allows any cycle you want. I could easily dial in a 7200 second cycle.

MarkS

Hatterasguy said:

I wish the 279 had the availability of a two hour cycle.

The 279 manual says the max cycle time is 100 minutes (1 hr 40 mins). I wonder why they picked that value. The display can show 3 digits, so it isn't a display limitation. Strange.

ChrisJ

I've considered changing all of my stuff over from 30 minute cycles to 1 hour this time of year.

I don't think it effects comfort much if at all.

ChrisJ

Hatterasguy said:

Push (eliminate!) the envelope.

Go for two hours!!

It seems the EcoSteam is limited to around a 9 hour cycle so I was mistaken.

How's that Tekmar looking now?

Fred

If that thermostat has a mercury bulb, Make sure the thermostat is level. A 5 or 6 degree swing is huge and not typical. It may be during the colder days the heat loss makes up for the over-run but on warmer days, if the thermostat is not level, the impact of that is more obvious.

exqheat

A good control that allows the thermostat to provide the data from hour to hour should adjust to all seasonal changes. You need a minimum time to fill the system. Further adjustment can be calculated from thermostat activity.

ethicalpaul

Kind of strange reply on an ancient thread, I'm going to flag it just in case.

exqheat

What is a flag?

ethicalpaul

............................................................................^^^

exqheat

What is a flag?

GGross

@exqheat
probably thought you were a bot. Sometimes bot accounts spring up here and resurrect old threads, they generally link some product or service though, just a misunderstanding.

ethicalpaul

I'm still not sure

exqheat

Ancient questions are the study of Ph.D. students. Curiosity is the energy for innovation. The beauty of these boards is the ability for questions to wait for the answer.