Desperately need routing advise for \"simple system\"

Bill_58

Well, looking at the prices of the Tekmar (haven't found the other yet), looks like the controller for the 4-way valve (if that is the Viessmann you are talking about), along with support hardware is well over $1200. Wow? Perhaps I misunderstood what you ment. For a rental property I plan to own for 5 years or less, there would not be a very high payback. Other options for less $$$?
Thank you, Bill

Bill_58

I have been speaking with several HVAC installation

persons in my area, and have been getting installation advice that appears, to me, to be unsound. Let me explain the situation, then what I want: I am seeking a contractor to replace a VERY old, oversized oil boiler. The boiler ran hot, spewed fumes, time to go! The replacement boiler I bought for a good deal...I Burnham 204 series II pilot natural gas boiler. The area that I am heating are two second floor apartments...each one zone, the exact same size, each the same type/amount/ of cast iron radiators (equal zones in every way) totalling 1500 square feet. I have contacted several installation persons to look at my system, and all said that they typically do NOT use a boiler bypass...or balancing system...to maintain boiler temperature. I am concerned about this since I have read several points recommending otherwise. I found a competant installer that said he will "build the design I wish" so long as it makes sense to him. So, here is what I want: two zones, with bypass allowing at least 140 degrees to the boiler at all times. I prefer NOT to use any "manual" globe valves, etc., but want something more precise and automatic...could be electric multiposition gate style balancing valve(s), etc. I do not really care if circulators are used or zone valves, but like the sounds of the white-rodgers 1311's with end switches. I would like to have outdoor reset, and have been looking hard at the tekmar 256 as an economical choice. I live in central PA. I want to know if outdoor reset is a good option for this particular cast iron system. I "think" I need a primary loop with circulator "forcing" the bypass and running all of the time, as well as a secondary circulator(s) in the secondary loop, but have also gotten mixed feedback about this as to it not being efficient since "too much" hot water is returned to the system. A sketch of a basic system would be great...and again, I am not installing myself, but simply looking for a "modern" system with bypass, and is relatively economical to run. I am desparate for some advise, and would even contact someone by telephone if need be. I can scan sketches and receive scans to finalize a basic system. I so greatly appreciate the advice. I will include a "starting sketch" of my system that does not include air separator, etc...just basic zoning. I am open to suggestions! Let me know if you need more info. Thank you, Bill

Bill_58

oops...each zone is 750 square feet

I was unclear in apartment sizes...they are two apartments "totaling" 1500 square feet, and are 750 ft'2 each.

Constantin

I'd consider the following...

... if you're going to replace the near-boiler piping and/or the boiler, it makes a lot of sense to simply start over.

Below is a suggestion using a 4-way valve that affords boiler protection and that minimizes the number of circulators in the system. If the zones are small enough, you may even be able to get away with just one pump and two zone valves. The 4-way valve not only protects the boiler, it's also perfect to modulate the temperatures going out to the apartments. The Outdoor reset can apply to the valve and/or the boiler.

An integrated controller/valve/boiler solution can be had from Viessmann. Tekmar also has a 4-way valve on the market along with the necessary controllers to retrofit most of that capability to just about any boiler.

PS, please use your image program to resize your images to be less than 500 pixels across. Otherwise, everyone will have a hard time reading your post as it stretches across the screen. If you're a windows afficionado, I recommend Irfanview - great program and free!

[Edited to show the flow pattern]

Bill_58

SP, would the tekmar system use...

the mixing station and actuator to control the 4 way mixing valve? Would there be no need for a pump on the boiler side of the actuator, or is it counting on the loop pump to circulate through the valve and thus direct flow through the boiler (it just seems like it would need a pump at the boiler). Thanks for the advice on the pictures...I downloaded it an I am set for the next sketch! If you don't mind, can you stick with me on the design of this? You have offered the most help yet. I will also attach a drawing from a technical support guy from Burnham...tell me what you think (there really is no control for return temperature). Also, in your sketch, I assume that if using zone valves instead, the pump would go just before the "T" of the second zone and the 4 way valve. Lastly, can you show be waterflow within your diagram? All of this would be very helpfull. Thank you!

Constantin

Sorry, I'm but a mere homeowner myself...

... I cannot speak about prices, as I don't know what they are and pricing isn't allowed to be discussed on the Wall in general.

I would have a professional make some proposals for you to review. Perhaps it makes more economic sense to pipe a simple bypass past the boiler and to vary the boiler temperature with the OR controller.

Another way to do it is pri-sec but all the labor involved in getting the piping on the wall may cost as much as the Tekmar system. Thus, compare your options on total cost, not the cost of the materials alone. The labor may be substantial.

As for the above diagram, the boiler circuit does not need a separate pump. My home is piped as shown, but with 6 circulators pulling heat from the boiler as needed. John Siegenthaler describes 4-way-valves vs. injection mixing in great detail in this article at PM Engineer Magazine. Oh, and here is a link to Viessmann.

Bill_58

What about this drawing? comes from...

...the pmengineer website. Both loops in my system will have equal demand, so I will need balanced temperature. It still doesn't quite solve the regulation of boiler return water temp, but looks like with high mass radiators, heat loss would not be as much, especially when combined with the primary loop configuration. What-da-ya think? I assume I would need to connect the last crossover bridge to end the loop.

Bill_58

Bill_58

what about this?

Doesn't quite sold the temp return to the boiler, but has "some" built in protection I suppose...what do you think of this?

Constantin

Primary-Secondary Piping

... is probably the least expensive way to keep just about any boiler happy. Dan has a published good book on the subject. At the very least, add the Pri-Sec piping, it will protect the boiler from low return temperatures that your emitters may allow when used in conjunction with a OR-controller.

Bill_58

here may be a solution...

Here is a Taco variable speed injection motor which looks like it has built-in control to add one or more temp sensors (return watertemp). It can be set up to turn "on" with temp increase or decrease. Check out this link to see what you think. http://www.taco-hvac.com/uploads/FileLibrary/102-143.pdf Look at page 1, second picture from the top. I guess it would be set up to run faster until the system began to heat up, then slow to a stop as the system return temp increased to a set-point. Thoughts?