Taming the Beast - Oversized Boiler Upgrades

AdmiralYoda

My boiler is 40% oversized and will cycle on pressure when using a setback or it's cold out...15F and below.  My radiators are screaming hot at 4 ounces of pressure, so I'm going to try and tame this beast.

I finally installed a Vaporstat.  It will still cycle on pressure, just less of it which will hopefully translate to fuel savings.

Next up is a Macromatic TR-6512U delay timer.  I'm going to attempt to start using a 2 or 3 degree setback overnight.  The delay timer will allow me to automatically turn off the boiler once pressure starts to build and let the hot radiators give up their heat to the room without the boiler running.

Anyway....here is a pic of phase 1 of the upgrade.  I was actually surprised at how large the Vaporstat was.

ethicalpaul

If just a time-based delay doesn't work out, let me know in this thread and I'll share my pressure-triggered delay setup which triggers on whatever pressure you want. I have mine set to cut out for 20 minutes if pressure gets to 4.5 inches of water column (2.6 ounces/sq in)

AdmiralYoda

Thanks @ethicalpaul that sounds like a really good idea!  If you could share that info I'd appreciate it.

The real reason for all these upgrades is I'm installing an Ecobee smart thermostat and a bunch of remote sensors.  It will want to adjust the temperature based on our habits so I'm just trying to prevent fuel from being wasted due to excessive pressure.

Jamie Hall

AdmiralYoda said:

Thanks @ethicalpaul that sounds like a really good idea!  If you could share that info I'd appreciate it.

The real reason for all these upgrades is I'm installing an Ecobee smart thermostat and a bunch of remote sensors.  It will want to adjust the temperature based on our habits so I'm just trying to prevent fuel from being wasted due to excessive pressure.

Instead, sadly, you will waste fuel based on raising the thermostats up and down...

AdmiralYoda

@Jamie Hall that may happen....and if it does I can disable that feature.  What really sold me on the Ecobee was that it knows the outdoor temp and will adjust heat anticipation accordingly.  It may be gadgety...but it will be fun to use.

The Steam Whisperer

BE forewarned that most of those "Smart thermostats" only work with forced air systems and will cause short cycling in steam systems. WE just removed one a few weeks ago installed by another contractor and the homeowner says the house is so much more comfortable than it was with the old stat.

Kjmass1

You are going to like the Ecobee with remote sensors, especially when combined with a vaporstat and delay timer. I personally use a delay time for my 2-3x oversized boiler. Timer only kicks on in single digits, or setback from travel.

This shows 4 different rooms along with the blue average line that the Ecobee uses to cycle on and off. Fairly typical home- a cold back office room, a warmer kids room when the door is closed, etc. They also all have varying heatloss throughout the day- and radiator response time (compare orange living room to red office). Also notice how once the sun comes out, outdoor temps rise a bit, and almost all rooms are consistent by the end of the day.

That said, if I was using a "dumb" thermostat in my living room set to 70F, all of the bedrooms would overheat at night and would be 1-2 degrees warmer. By averaging the cool with the warm, consistency can be achieved. By the afternoon, the rest of the home would feel cool as the living room is the warmest room in the house.

AdmiralYoda

@Kjmass1 this is essentially what I am trying to achieve.  Still on the fence on if I want to try a small setback overnight like 2 to 3 degrees.  Thanks!

Kafox15

We have an ecobee and do a 3 degree setback at night (68->65) since we like it cooler to sleep. The ecobee (mine at least) has a tendency to overshoot the setpoint when recovering from a setback in the morning but when maintaining 68 during the day, it doesn't overshoot too bad.

Kjmass1

AdmiralYoda said:

@Kjmass1 this is essentially what I am trying to achieve.  Still on the fence on if I want to try a small setback overnight like 2 to 3 degrees.  Thanks!

You should be able to do that with the vaporstat and timer no problem. One thing to watch is when it gets out of it's rhythm- say a setback in the morning. Ecobee might think it will take 20 minutes to reach temperture, turns off, sees it wasn't enough, turns it back on a little bit later to catch up. In that case your timer will reset back to zero. Doesn't happen often but can with drastic thermostat changes or big outdoor temp swings.

AdmiralYoda

@ethicalpaul would you mind sharing the details on your pressure switch with time delay?  Sounds a bit better than a plan old time delay.  Thanks!

ethicalpaul

Sure, let me gather up some info

JUGHNE

Admiral, pressure controls are considered safety devices.....they should not be able to be isolated from the boiler internal cavity. Your valves below them will do just that.

dabrakeman

There are some other approaches for others reading this who might be using or considering using the Ecobee and also want to "tame the beast". I too have a oversized boiler ~50% and have managed to handle setbacks and extreme cold just with the thermostat and remote sensors. I certainly see the positive aspects of the time delay setup (and may still try it in the future) and don't want to take away from that but this may be a simpler approach others might want to try, particularly if your main issue is just wanting to do setbacks and dealing with the recovery. Basically you will be just using the activity scheduling of the Ecobee to control 30 minute on and 30 minute off cycles during your recovery.

1) Turn the Smart Recovery off on the thermostat. If you are already reading this forum you probably know more about what you want your personal steam system to do than the thermostat manufacturer does. Knowing when exactly your boiler is going to start firing is the first step in controlling your cycle times during recovery.
2) Use the remote thermostat or thermostats for control since wall mounted thermostats often can have slow response to actual temperature due to temperature of the wall itself or air behind it. Slow tstat response leads to longer cycles.
3) Figure out how long it takes particularly with a warm system to get to a point where you start building undesired pressure? If you can make it 30 minutes then you can use the following approach. Ideally run your boiler for 30 minutes after it has been off for exactly 30 minutes and verify with a low pressure 3psi gage you are still under about 0.25psi. Really should not be building pressure beyond what you register under normal run conditions after your mains have closed.
4) Assuming so, then a nice feature of the Ecobee (and maybe other thermostats, I don't know) that you can use is that there seems to be no limit to the number of activities you can program for a given day, or at least I have not run into the limit if there is one. Scheduling times of the activities though are limited currently to 30 minute increments and thus the discussion above about whether you can run for 30 minutes straight without getting into pressure trouble. For me 30 minutes is pretty optimal. Radiators get to ~75% full with no pressure buildup. So, all you have to do during the recovery is to break it up into a few 30 minute on and 30 minute off increments. For example, I do a 5 degree recovery in the morning M-F (59f-64F) and 6 degree recovery on weekends (59F-65F). On weekdays I start the recovery at 5AM by using an activity created with a temperature set at the target recovery temperature of 64F. At 5:30AM another scheduled activity shuts the boiler down by calling for the 59F temperature again. At 6AM another activity calls for the target 64F and at 6:30AM again another scheduled activity shuts it down by calling for 59F again. I program in a 3rd cycle in this manner and that is usually enough with the heat dissipation between cycles even on coldest days to get me up the needed 5 or 6 degrees.
5) Doing this it is also best to set the normal swing control at 0.5 deg. This also give better control on the recovery. Note that for each activity that you create you can assign it to be "normally home" or "normally away". "Normally home" keeps it using the set default swing. If you assign it as a "normally away" activity Ecobee automatically adds 1.5 degree to the swing. This is fine when you really are away and does save money but can mess up your recovery so make sure all your recovery steps set as normally home. I actually use the normally away designation during the day when I am the only one home alone working in my now home office (did I mention I am a cheapskate). When the wife gets home we go back to tight temperature control... Note, you can also set a minimum runtime which is good just to prevent a short cycle before a setback start. Set it at something that assures you get steam to your radiators. I use 15 minutes.

A timer will give better control in that your are not limited to the 30 minutes increments on time and between cycle time (I have asked Ecobee to consider giving us 10 minute increment control) and it will be more able to handle wider range of environmental extremes without ever having to worry about pressure. That said, the tstat method outlined here would work for many with fairly satisfactory results. If you already had the Ecobee it would be worth trying before doing further investments.

Attached screen shot shows a typical setback and recovery the way I set it up.

If you are able to do it WITHOUT GENERATING PRESSURE setbacks do save money. Total energy required to heat a house is a function of total outdoor vs indoor temperature differential.

ethicalpaul

This is a really good option for those with thermostats that can do it!

I can even do a bit of this because even my old school Honeywell has 4 time segments I can program.

AdmiralYoda

Oh man...thought I had replied to this.  Thanks to this website for keeping my draft response...here goes.

The reason I installed the isolation valves like that (and that doesn't mean I'm right) was to be able to test the controls.

I can close the valve to the Vaporstat and 20oz gauge, build pressure and then test the P-trol.  It will also allow me to close both, AND the king valves on the risers and mains to build pressure for a true blowdown.  The 30psi gauge will still read pressure in this case.

Of course that may sound nice on paper, but if I'm violating some codes or industry best practices, I'm all ears!

Kafox15

Wow @dabrakeman that is great. My biggest gripe with ecobee is overshooting on recovery and that just may solve my problem. I can add another vote for 10 minute intervals with ecobee if you like. Is there an existing feature request or something I should reference so they will know what I am talking about?

AdmiralYoda

@dabrakeman After re-reading your post I totally agree with your approach, but I don't think it will work well in my application.

When it is cold (<25F) the boiler is running often enough that the water remains hot. In this case I will begin to build pressure in as little as 9 minutes. At >35F its closer to 20 min. This is just at a constant T-stat setting, no setback.

I'm taking a two stage approach. First installing a low pressure switch and a delay timer that will open the t-stat circuit and shut down the boiler for a set time such as 20min or so. This will allow the screaming hot radiators to give off heat while not burning fuel. After the 20min if the T-stat is still calling for heat the cycle will repeat.

If I decide to try a setback in the morning, probably only 2 or 3 degrees, I'll probably program the Ecobee to have multiple stages. Something like 64 to 65 degrees at 5AM, 65 to 66 at 6AM, etc.

This will allow the radiators to give off their heat in an orderly manner without the boiler constantly cycling on pressure and wasting fuel. The slow and even approach should also prevent an overshoot, hopefully.

dabrakeman

@AdmiralYoda Seems interesting to me that you build pressure so quickly only being 40% oversized. I am at least 40% oversized and certainly don't build pressure anywhere near that fast. I have a couple Gorton 2's on both my mains as well so get steam that far pretty quick. Only time I would build pressure that fast is back when the boiler actually was cycling on pressure. I am not sure why the difference in our systems but I only have my system to go off of... Maybe we can explore offline.
If you can't withstand a couple back to back 30 minute runs after a cold start then the method probably will not work for you. You could benefit from the 10 minute increments if Ecobee ever offers it.

I previously tried breaking up the recovery simply with temperature stages and it was less predictable. For one thing it could take longer and thus longer run time to gain the 1 or 2 degrees on a 10 degree morning than a 30 degree morning. Perhaps a bigger problem is that you don't know when a normal temperature hold cycle is going to occur during your setback hold. If it came on 15 minutes before your scheduled recovery start (which it might do anyway if you don't turn the Smart Recovery off) then you could end up with a cycle that is 15 minutes + the normal time it takes you to get your +1 or +2 degree recovery. Forcing the 30 minute recovery cycles is more predictable. I failed to mention in my previous description that I also put a 30 minute activity in right before my recovery taht is actually lower than the setback temperature by a degree just to help ensure that the boiler is not running before my first 30 minute recovery cycle is scheduled to start.

@Kafox15 The more voices the better. I have generally had good rapport with them using their email based support. Any words you can put in supporting potential steam users needs for either a max runtime (with set delay) setting option or finer time increments for schedule setting would be beneficial. Nothing to lose. You could reference this forum and discussion to them. All just striving for greater efficiency.

Kjmass1

It’s be great to have a bit more options in ecobee. Max cycle runtime, max minutes per hour, and delay after run would all be easy improvements. 

EBEBRATT-Ed

@AdmiralYoda

As @JUGHNE mentioned you cannot have valves under pressure controls. You MUST take the one off under the gray Pa404A control at the very least. I would take them both out. If your insurance company sees that they wouldn't be happy

AdmiralYoda

@EBEBRATT-Ed and @JUGHNE I'm all ears man.  It will take a couple minutes to take them out and if it's the best idea I have no problem with that.

Just one last question though.  The answer may wind up being so painfully obvious as to why my isolation valves are a bad idea but here it goes....  Out of curiosity, how do some steam companies perform a blowdown with King valves when doing maintenance to clean out a boiler?

Here is my assumption and I welcome any thoughtful kicks in the arse if I'm way off.  If a boiler had king valves on the risers and mains there would be no where for the boiler's pressure to go except higher and higher.  A very qualified steam expert allows the pressure to build to some reasonable psi (on the 30psi gauge that isn't bypassed)  and opens the boiler drains at various points to suck out the dirty water and any sludge out with it.

And here is my assumption.  If I did not have these isolation valves and if a qualified person shut all the king valves off and fired up the boiler....the lowest pressure safety device would kick in and would never let enough pressure build up for a proper blow down.

The only way around this is to isolate the pressure safety devices by electrically completing the T-Stat circuit by jumping the R and W wires (in my case) at the ignition module.   Thus completing the equivalent of a continuous call for heat yet jumping electrically around the pressure safety controls.

AdmiralYoda

 Again, I'm a DIY'r and tinkerer....that always leans on the side of safety and caution which I'm thinking my family appreciates.  So if my logic is incorrect....I'm all ears.

AdmiralYoda

Just bringing this back to life if someone has some additional input. How does a pro do a pro blowdown with king valves if the pressure controls are not bypassed? Bypassing them electrically?

EBEBRATT-Ed

@AdmiralYoda

Boilers can blow up if over pressurized. So you have 2 things on the boiler to prevent over pressure.

Safety valve set at 15psi.

Pressure control with a maximum setting of 15 psi.

You can't have valves to isolate any safety control. No valves between boiler and low water cutoff, no valves between pressure controls and the boiler, no valves between the safety valve and the boiler

People can get mixed up and open or close valves leaving the boiler in an unsafe condition. You may know what your doing and never have an issue.

What happens if you sell the house?

What happens if a kid goes down there and starts playing with things?

Boilers have been known to blow up go through the roof and travel several city blocks


In your case, because you added a vapor stat maybe technically the vapor stat could be isolated but not the other pressure control.

But I don't wan't to open that can of worms

AdmiralYoda

@EBEBRATT-Ed I get it. They will be coming out, no arguments here. My good intentions could turn out to be not so good in the long run. Exactly why I put this picture here for the pro's to weigh in.

But aside from what I've done....back to the original intent... How do you pro's perform a blowdown with king valves. My understanding is that you allow the boiler to build a reasonable amount of pressure, then release it through various drains to suck out the muck.

With the safety controls in place the only way I can see this being accomplished is by electrically bypassing them during the blowdown.

ethicalpaul

You can adjust your pressuretrol up to 5psi or whatever. But since you have the vaporstat, as you said, it only goes so high so you'd have to jumper it.

AdmiralYoda

I like the idea of letting the professionals do their thing and jumper or adjust whatever they want to accomplish whatever they are trying to do (like a pressurized blowdown).

My isolation valve approach might look good on paper but with the wisdom of this forum in practice it could potentially be problematic (or worse).

Let this be a lesson kids....listen to your elders.

EBEBRATT-Ed

@AdmiralYoda

Most don't bother with a "pressureized blowdown" simply because most residential steam systems don't have king valves. Do they do any good? Maybe, can't hut if you want to pay for the valves.

But if you set your vapor stat as high as it will go and blow the boiler down when the pressure gets up to the vapor stat setting believe me you will have plenty of pressure

AdmiralYoda

@EBEBRATT-Ed every now and then I test my pressure relief valve at the pressure the P-trol kicks in, around 10oz.  There is plenty of pressure to make things move.

Since I'm the one repiping the boiler....I'm on the fence whether or not to use king valves.  @ethicalpaul is my inspiration as our systems are about the same size and I plan to use a Peerless 63-04L...forgot the exact model but the same as Paul's, Peerless's smallest one.

King valves are cool buuuuuuuut do I need them?  Meh.  Do I want them?  They are shiny so yeah.

ethicalpaul

63-03L