Heating Help

As far as I know,

@ December 20, 2010 10:29 AM in Once again - cph setting for steam

CPH does influence both how OFTEN and how LONG thermostat calls for heat, and an intelligent thermostat will adjust its algorithm based on the actual system performance and a set of hard-coded assumptions (like outside wind and temperature).

CPH = 2

@ December 18, 2010 5:49 PM in Once again - cph setting for steam

Mark, thanks for making this experiment!

I have a question - while the rads were barely heating - was the house still at the set temperature? Because if it wasn't - then this is a different question - with any CPH thermostat should be able to achieve its goal, and it does in my case.

But if it was - the goal was achieved even with the rads barely warm and this sounds like some fuel saving.

Thanks for the link

@ December 16, 2010 8:46 AM in Once again - cph setting for steam

I will definitely read it.

I also have somewhere an old Honeywell patent that describes their Intelligent Recovery algorithm and how thermostat adjusts its running time. Somehow I think not much has changes in this algorithm over the years.

Mike

@ December 15, 2010 10:29 PM in Once again - cph setting for steam

the short cycles don't heat the house, but they do heat up the water in the boiler several degrees, so that the next long cycle will start producing steam faster, and so more of the long cycle will be spent actually heating the house than bringing the water to boil. So I don't think the energy is completely wasted during these short cycles.

Your explanation of why I may be seeing fuel saving with cph = 5 is a good point and might be true. But it does not feel any more comfortable when I'm using cph = 3, and subjectively, cph = 1 provides much less comfort than cph = 5 because of the serious temperature swing.

So, the bottom line seems to be: in my house, cph = 5 provides more comfort and uses less fuel than cph = 1. I know this is wrong :) and was wondering if anyone has some numbers that would show how cph = 1 uses less fuel than higher setting in their house.

Mark, this sounds like

@ December 15, 2010 7:21 PM in Once again - cph setting for steam

your house is very well insulated, unfortunately not the case with my house. When house is well insulated, there is no need for the thermostat to overshoot in order to be able to maintain cph = 1, and thermostats can learn by adjusting their algorithm. In this case cph = 1 must be optimal. In my case it needs to overshoot, because otherwise it'll have to start more than once an hour to maintain the set temperature.

In other words, it seems in a poorly insulated house it may turn out to be cheaper to start more often to maintain water and piping warm.

Hi Mark,

@ December 15, 2010 5:47 PM in Once again - cph setting for steam

Yes, I do keep track of that, but I don't have any logging devices so it's not very valuable. With cph = 5 boiler still goes on averagely 3 times an hour, one time for 15-20 minutes, and couple of times for 3-4 minutes, that just keeps the pipes warm. This naturally depends on the outside temperature, but the pattern is the same - one longer time that would slightly overshoot the set temperature, and 2-3 shorter times. I wouldn't call this short-cycling. Note that this is the algorithm chosen by the thermostat, which seems kind of smart to me this season. Getting from 3-degree setback in the morning takes 25-30 minutes run, again depending on the temperature outside, pressure usually does not reach cut out or even start to rise noticeably.

With cph = 3 pattern is about the same, but naturally run times are little longer as thermostat needs to overshoot more, and it's 1-2 short runs per hour instead of 2-3. With cph = 1 runs are longer (40 minutes from setback) which results in cycling on pressure at the end of the cycle (sometimes) and 2 degree overshoot is normal. Didn't notice short runs.

Once again - cph setting for steam

@ December 15, 2010 3:59 PM in Once again - cph setting for steam

I know it should be set to 1, it's all over the Internet. :)

However, has anyone actually measured  fuel consumption (boiler ON time) with different setting of cph for steam? I am asking because I have been doing this for the last several weeks, and I conclude that the actual ON time of my boiler is slightly less with cph = 5 than with cph = 3 or 1. I run with the same setting for a week, then take this week's HDD data from degreedays.com and calculate the amount of consumed gas per degree day. I ran 3 weeks with cph = 5, 2 weeks with cph = 3 and this week I am running with cph = 1. Outside temperature range has been pretty wide during this time. It's really hard to make this a 'clean' experiment, but averaging per week gives it at least some sense. For what it's worth, each week with cph = 5 shows less gas consumption per degree day than each week with cph = 3, and the last four days with cph = 1. The difference is small, but it does look better for higher cph.

Any thoughts on that? My house is poorly insulated overall, piping is insulated pretty well. Thermostat is VisionPro TH8110U1003.

Oops, sorry, missed that you are running oil

@ December 9, 2010 9:59 AM in let the data begin...

I'm just looking to get an idea of what those numbers can be... OnTime/HDD is good, but not with a modulating burner, I think.

jpf321

@ December 8, 2010 11:32 AM in let the data begin...

May be I missed but I can't find among your charts data for Therms/HDD or CCF/HDD. Aren't those the most direct indicators of how efficiently (in terms of cost) the system operates?

This thread may be of interest to you

@ December 1, 2010 11:03 AM in Gorton D valve

http://www.heatinghelp.com/forum-thread/132580/Pressure#p1206604

Below is my posting from this thread. I also remember someone posted a picture of a simple test rig they created for testing pressuretrols, but I can't find it now. I think I would start with getting a 0-3 PSI gauge to see what is really going on in the system.

Most of these pressuretrols are off in the lower scale range, at least the 3 I have were all off. I did a 'live' adjustment (which I don't know if it can be recommended but it worked for me). With pressuretrol set to desired settings, I make the boiler run for a while so that pressure starts building up, and then I watch the pressure on the gauge and when it is close to the desired cut off, I start slowly turning the pressuretrol's adjusting screw (that adjusts cut-in) down until the pressuretrol trips. This always happened before the spring would go loose from the screw, which is also a possibility. Visually, during all this time the cut-in setting was on 0.5.

I think that

@ December 1, 2010 10:18 AM in Gorton D valve

your pressuretrol needs to be adjusted - it does not shut down boiler at 1.5 PSI. This usually can be done easily, but a 0-3 PSI pressure gauge would be helpful. There have been several threads here discussing this.

In fact,

@ November 30, 2010 7:50 PM in Vent damper disabled?

this is exactly the case, the chimney didn't have steel liner until recently.

From my (very small) experience

@ November 30, 2010 5:06 PM in Gorton D valve

If they do it after the radiator is filled but while the boiler is still running - this may indicate that your system develops some noticeable pressure closer to the end of the 'on' cycle (boiler runs for a long time and pressuretrol does not trip when expected).

If they do it after the boiler shuts down - they are actually taking air in because steam is condensing, creating vacuum. It is normal, but hissing may again indicate that the pressure was somewhat high at the end of the cycle.

icesailor, thank you for your concern

@ November 30, 2010 4:46 PM in Vent damper disabled?

and I am thinking along those lines too - was the switch left in this position inadvertently or may be there was a reason.

The control seems to be functioning properly - it opens when thermostat calls for heat, and only after it's fully opened the burner comes on. After thermostat breaks the call and burner stops, the damper closes. Both operations take no more than 15 seconds. I checked all this several times. I would hope that if the control was broken and left in the open position on purpose, then whoever did that would had left a note.

Is another possibility - the damper does not really help with operations efficiency on this boiler and though it was installed by code, it was left open in order to never cause any problems?

Thank you for your advice

@ November 30, 2010 3:23 PM in Vent damper disabled?

It is intermittent pilot.

This is interesting

@ November 30, 2010 9:18 AM in Vent damper disabled?

Thanks for the reply. The vent damper has been initially installed with the boiler, and the inspection guy didn't say anything about it. But may be he didn't say anything _because_ the damper was in the 'hold open' mode?

Not considering legal aspect - is it better to have the functioning automatic damper? Or it depends? Or are there opposite opinions as with almost everything else? Is it possible that damper shuts in some kind of condensation in the boiler?

Vent damper disabled?

@ November 29, 2010 7:56 PM in Vent damper disabled?

I noticed that the FieldControls GVD-6 vent damper, installed on my gas boiler, was in the 'hold open' mode set by the switch on the damper. I switched it to 'automatic' mode, and it seems to be functioning properly. However, I am wondering, can there be a reason why this control would be disabled on purpose, so that I should not enable it?

What did they do?

@ November 15, 2010 3:46 PM in What did they do?

I posted this in the Pressure thread, but probably shouldn't have clogged that thread, so I'll open a new one. My steam system changed the pressure on which it operates during the cycle after two events. I have a 0-3 PSI gauge, which I spent a lot of cold mornings in the basement watching during the last season.

Before: the pressure would stay on about 5 oz. after the steam is ready to go, and would gradually go up to 8 oz. after 30-35 minutes and then thermostat is usually satisfied, so vaporstat never trips. The water in the glass was clear but somewhat brownish, and its level would go down from 3/4 to 1/2 of the glass and would move noticeably around the 1/2 mark when the steam is being produced. Radiators are warm within 20-25 minutes of cold start. I always could here the main vents hissing when the first portion of steam goes out, and the radiator vents hissing after that (not loud but audible, kind of liked that sound).

After: the pressure stays around 1.0 oz during the whole 30-35 minutes, with a very small build up to 1.5 oz. towards the end of the cycle. The water in the glass is clear and clean, much lighter than before. Instead of going down when the water boils, it goes just a little up, and does not move much. I can't hear ANY hissing from the vents, main or radiator vents, but the radiators are still warm within 20-25 minutes of cold star - this did not change.

What happened:

1) the guys changed the chimney liner system for the boiler/water heater flue;
2) while doing this they flooded the boiler.

When I came home, the 0-3 PSI pressure gauge was showing about 1.5 PSI and the glass was full of water. I started draining the boiler and pretty soon the water level in the glass returned to normal, and the pressure gauge returned to 0. I think I drained several quarts of water, so it wasn't too much of a flooding, I guess.

But after this two events the behavior changed. I thought the gauge went south, but this does not seem the case. I also disassembled and cleaned the pig tail and all the orifices that carry the gauge and the vaporstat. Because I can't hear the vents hissing anymore - I think the pressure that the gauge shows is real. All the radiators are warm within the same time as before, the system seems to work not any worth. I'm just trying to understand what can cause this change in behavior, whether something broke or is it normal.

Brian, most of these pressuretrols are off

@ November 15, 2010 3:09 PM in Pressure

in the lower scale range, at least the 3 I have were all off. I did a 'live' adjustment (which I don't know if it can be recommended but it worked for me). With pressuretrol set to desired settings, I make the boiler run for a while so that pressure starts building up, and then I watch the pressure on the gauge and when it is close to the desired cut off, I start slowly turning the pressuretrol's adjusting screw (that adjusts cut-in) down until the pressuretrol trips. This always happened before the spring would go loose from the screw, which is also a possibility. Visually, during all this time the cut-in setting was on 0.5.

Can the system behavior change

@ November 14, 2010 11:30 AM in Pressure

from installing a new chimney liner system for the boiler? My steam system used to operate in the 8 oz. range throughout the cycle, and immediately after the installation of a new liner the pressure never goes above 1.5 oz., so basically I now have the same picture as crash2009. What have happened?

It's all about the formula

@ November 8, 2010 4:28 PM in Honeywell TH8110U1003 strange behavior

The thermostat has a built-in algorithm by which it calculates and adjusts on/off times. The algorithm's behavior is determined by a number of coefficients, some hard-coded (like outside temperature on VisionPro), some adjustable - like CPH on most thermostats, or, on VisionPro - temperature correction setting. Obviously, my old thermostat used slightly different algorithm than my new thermostat, so even with the same values of the coefficients, the behaviour was different. However, I did come to like my new VisionPro better and decided to stay with it.

As for your question, lower values of CPH are in general recommended for steam heat system, many sources say it should be 1 or 2. However, this does depend on each particular house (size, insulation of walls, insulation of steam pipes, living patterns of inhabitants like tolerance to chilly air and so on :)), thermostat - what algorithm it uses, and also on temperature outside, so I would say that value of 3 (or even 4) is not unthinkable for steam system - it can provide more comfort for the same or just a little more money than hard temperature swings of CPH = 1.

Yes, it does now!

@ October 15, 2010 9:10 AM in Pressuretrol and standing pilot

Thank you very much for the information, Tim, JStar and Charlie.