reset w/o condensing: Burnham Revolution? other choices?

Unknown

with standard controls , look into the Taco I series mixing valves . The have an outdoor sensor control built into the mixing valve itself . I saw them at the last Wetstock and might try one on my own boiler for the same scenario you have . They look pretty straightfoward to install .

R. Kalia

how can I do this?

Hi, I'm a homeowner. After reading about all the issues involved, I figure I need outdoor reset and constant circulation (for lower noise, smaller temperature fluctuations, and slightly increased efficiency), but I DON'T need a condensing boiler (which would be more expensive and/or less reliable, and no more efficient in colder weather since we have CI rads and CI BB).

Certainly I can use any CI boiler plus mixing valves, but I haven't met any contractors in my area who appear clear on this concept or have any experience installing full-temp-range reset systems with CI boilers and radiators. (The 140-180 reset range is useless.)

One alternative is the noncondensing Burnham Revolution, which appears to have an injection pump and P/S piping built in, and will produce water at 55F and up, much like a condensing boiler. Is this boiler a good choice? Is it as reliable in the field as a standard CI boiler? Is it so expensive that I might as well get a condensing boiler?

Are there any other boilers that meet my requirements as described above? (I can't ask just any contractor because they usually just push one brand, typically a cheap CI boiler with bang-bang control. I'll have to call the mfg and ask for the name of a contractor with specific experience.)

Thank you very much for your help!

Tom Stayer_2

Couldn't help myself Wallies...
take a look at the MZ boiler, this is a condensing boiler and loves low water return.

Try www.mzboiler.com and call me or email.

R. Kalia

(a) the MZ condenses, which I wanted to stay away from (see original post); however, I do realize that the MZ is very reliable


(b) it does not modulate and it does not have built-in reset, but it costs more than boilers that do both


(c) your company couldn't refer me to even one MZ installer in this major metropolitan area.

DaveGateway

Wall hung boilers

like the Baxi Luna are modulating but not condensing. Good deal since it has a pump and controls. All you have to get is the outdoor probe for reset.

R. Kalia

Baxi fits my needs nicely. But I can't find a Baxi contractor either. Their distributor gave me one name, and he won't call me back, probably because he doesn't really know or doesn't want to do Baxi.

And I'm in the Chicago area!

Ken Wickre_6

Buderus, Burnham, Slant/Fin

Look at the Buderus GA124 CI boiler - sealed combustion, familiar Honeywell controls, 85+% AFUE - with the optional R2107 Logamatic Control. This can provide continuous circulation to one zone at full reset. The other zones are controlled with t-stats (at the same reset temperature, so pick the continuous zone to be the one with the highest temp requirement), more like high limits than stats. More information is availbable at www.buderus.net and be sure to check out their forum.

I like the Burnham Revolution for the reasons you stated, plus proven cast iron construction, familiar Honeywell controls, AFUE up to 88%. Look at their EC500 zone control with reset for your application of a high mass system.

The Slant/Fin VSPH at 85%+ AFUE - again cast iron, sealed combustion, familiar controls - matched with a control to reduce and regulate your water temperatures while preventing sustained flue gas condensation is worth investigating. A tekmar 361 injection mixing control would be what I would look at.

DaveGateway

Another option

The Laars Endurance is also non-condensing, modulating.
I don't think it's as pricey as the MZ. Laars has good support. Checkout
http://www.spnwonline.com/Templates/frmTemplateK.asp?SubFolderID=71&SearchYN=N

You'll find some other Asian brand wall hungs like Quietside, but I can't vouch for their support.

R. Kalia

Thanks for the suggestions! I looked up the web pages and they don't explicitly say that the Slant/Fin or Buderus boilers produce low-temp water (Burnham Revolution clearly does).

Based on external appearance, I would guess that the Burnham EC5000 control is a rebranded Tekmar, although I don't know which model.

Tom Stayer_2

To be hung...

Why not condensing boilers? “The proof is in the pudding” one may say. Case in point- MPI has an employee that choose to put a MZ in his home. The home had/has hot water gravity with cast iron radiators. He found that with cycling the boiler on and off with the call for heat via tstat, his feul consumption was reduced from 30% to 40%. No additional pumps, exp tanks, bypass piping were required- even the original huge piping mains were not replaced.

MPI also offers a modulating control for the MZ and can be connected in conjunction with a 3 way valve kit which makes for an easy DHW installation. If you decide to take another look at installing the MZ, I would like to assist you in finding a qualified contractor near you. Otherwise, a simple training can be arranged.

Ken Wickre_6

It's all in the controls

Cast iron boilers have to be protected from flue gas condensation. The Revolution does it with an internal injection pump in a primary/secondary piping configuration as you noted. The internal water temp of the Revolution will be maintained at 170° F to 210° F while the injection pump transfers a comparitively small amount of hot water to a larger amount of return water from the system - providing a reasonalbe reduced temp for the system. The EC5000 is most comparable to a tekmar 370.

The Buderus Logamatic control provides protection by shutting down the system circulator if the boiler water temperature falls below 104° F and the burner is firing. When the system requires low water temps, the burner is on (and off) for longer periods of time. Because the boiler is a "hot" boiler on full system reset, monitored by a room temp unit in the continous zone, the inefficiencies of cold starts and cycling are eliminated.

The tekmar 361 control in the instance of the Slant/Fin VSPH provides the reduced water temp the system requires, regulates it based on outdoor temp, and protects the boiler from flue gas condensation by varying the injection pump output (similar to the Revolution internal pump).

These cast iron boilers all provide AFUE's over 85% and are a good value, have proven themselves, and are reliable. If you have done all you can to provide the best structure to hold the heat you are going to generate, have invested in the best system you can justify (zoning, reset, pipe insulation where necessary, etc.), then look at your heating plants - all the way up to through the condensing units.

With the research you are doing, and the advice of a reputable contractor you may select, I'm convinced you will be happy with whatever choice you make.

Boilerpro_3

In Chicago

If you want, Give me a call(815 857-2339 or E mail. I'm originally from there, but now located west of Chicago, and do the type of install your talking about quite regularly...A simple cast iron boiler with mixing valve in a cast iron system. I recently did a steam install up north and have another planned for just east of Gary. I also know a good guy up north too. Sort of strange there is almost no one listed on "Find a Professional" for Chicago. I may be looking at getting listed there.

Here's a picture of the type of install you're talking about. This is a two boiler install for a larger home (about 4,000 to 4,500 sq ft) with the boilers staged by a two stage thermostat. Both boilers provide heat to the whole home and only one runs must of the time and the second is kicked in only when needed (really cold weather or coming out of setback).

Boilerpro

from "Sweet home Chicago"

R. Kalia

yes but....

> Case in point- MPI has an

> employee that choose to put a MZ in his home.

> The home had/has hot water gravity with cast iron

> radiators. He found that with cycling the

> boiler on and off with the call for heat via

> tstat...

Works well only wih a single-zone system. Ours has two zones which cannot be combined (vastly different diameters of piping), and one of these has a load that varies with amoun of sunshine...

> MPI also

> offers a modulating control for the MZ and can be

> connected in conjunction with a 3 way valve kit


Never heard of that, and it wasn't on your web page the last time I looked.

I bet it doesn't work with the thermostat-turns-boiler-on-off method you descibed, since the water temperature will always stay much lower than the boiler's aquastat setting i.e. the lame will always be high. Unless you have a smarter way to modulate.

Unknown

Well....Not really Ken!

The internal pump of the Revolution basically modulates the water flow through the boiler relative to the boiler's ability to raise its temperature. If the boiler is encountering cooler return water, the flow decreases to allow more heat transfer while allowing the system water is gradually warm up. When the boiler has reached a more reasonable temperature, the flow through the boiler increases and the system temperature as well.

The Revolution can be equipped with a system limit, which will interupt the burner to establish a desired system temperature. A reset control can provide this function as well. The EC-5000 Energy Control is similar to the Tekmar 370 House Control and comes equipped with 2 Room Temperature Units with provisions for four. Sorry I did not respond to this sooner, but I have been in the Northern extremities of Maine conducting training and had no internet connection. Hope this helps.

Glenn Stanton

Burnham Hydronics

Ken Wickre_6

I understand

I know what you mean, just couldn't explain it as well - thanks for that. What I like about the Revolution in this high mass system is what Ron Beck from Burnham called "poor man's reset". A high mass system (cast iron or concrete) matched closely to the output of a particular Revolution boiler will have its water temp gradually rise to a required temp to satisfy the space, maybe only 90 or 100 degrees, and shut down. With the internal pump no additional protection for flue gas condensation is necessary. The limit would be necessary in a system with multiple zones and the possiblity of the boiler having to supply heat to a much smaller load than it was designed for. For example - 100MBH output boiler and four (4) 25MBH zones. The boiler supplying one zone in this instance would overwhelm it and we would see the system temperature possibly rise higher than we want.

The 55 degree minimum return as published has been an issue I have tried to overcome with the Revolution in snow/ice melt systems. What have you seen done with this boiler in these instances? Is the concern thermal shock or condensation? I have been investigating the use of proportional reset on an external loop to a conventional Revolution. With careful attention paid to the design, I can get slab proteciton (40 degree delta T at startup with a 25 degree design) and maintain well over the 55 degree minimum. Thanks for your comments. Ken

Unknown

My concern

with large amounts of cool return water over prolonged periods of time is with the variable speed pump within the boiler piping. It will need to ramp up to full speed every so often in order to protect itself. I am certain you are using a heat exchanger for the snow melt and something as simple as bypass piping on the heating lines to that will guard against return water below 55°F. Other methods such as blending valves or variable speed injection are even better.

Ron and I pretty much talk on the same subjects in the same way and I have heard him mention "Poor Man's Reset". In the case of a large mass system and closely sized boiler in the intermediate climate, the thermostat will probably satisfy itself before the boiler and system water temperature has had a chance to satisfy the high limit setting of 210F. If you have an indirect heater with this application, you will certainly need hotter supply water so priority will be a must. Hope this helps.

Glenn

marc

burnham RV

is a great cast boiler, we have installed over 100, with outdoor reset, we orginally started with a tekmar 1 stage boiler control, this worked very well, except for switching out of domestic, you would get a small temp. spike for about 30sec. then we switched to injection mixing, which pretty much nails the design temp. marc

joel_19

hmm

I'm curious as to where you are located??? In that you can't find an installer? ithink maybe i'll move. We've used the Viessmann Vitogas 100 which is cast iron and can be reset with very good results on straight baseboard. For a lrge water content system i'd use the vitotronic 200 control and a 4way mixing valve to give added protection to the boiler and allow more precise water temp contol. For something cheaper you could use a Viessmann vitogas 50 and just a simple Tekmar and 4way valve.

Roy T. Weaver

Modulating burners

One thing to consider when modulating atmospheric burners is, while gas flow is reduced, the air is not. This means you will burn less gas, but with a higher air mixture your efficiency just went off the scale. In most cases your actual gas bill will be higher with modulating the atmospheric burner then firing it on/off.

An optional control strategy for use with the Revolution would be to do your zoning with IFC pumps instead of valves controled from two stage thermostats. First call for heat energizes the zone pump, if there is enough residule heat in the system to meet the demand, the burner never comes on. If the temperature demand is not met and the second stage registers a demand, that signal goes to the Revolution
as a call for heat. The Revolution high limit will cycle the boiler in extreme temperature range. This will provide you with weather responsive controls without the need for programming, installing outdoor,
system sensors, etc.

In fact with a "standard" 82% boiler, a flue damper, and the controls described above your efficiency will be right in there with high efficency boilers without all their "bells & whistles," because of not maintaining constant system water temperature for the entire heating season. The efficiency is obtained by zoning,
variable system water temperature, and reducing loss up the breeching with the vent damper.