takagi as heat source for low temp radiant and domestic

heatpup

Thank you hot rod. Now would you dare stick your neck out and recommend a boiler and indirect?... preferrably a condensing boiler...

heatpup

I want to use a tankless water heater as my heat source for low temp underfloor and for high temp baseboard. I also want to use it for DHW production. What do you chaps recommend for DHW production other than an indirect? can i use a plate heat exchanger and flow sensor to fire the boiler when hot water is demanded? Will I have sufficient flow of hot water if I do? OR should I use an indirect as a separate zone? I would be quite upset if I did the former and ran short of hot water... then I would be in hot water.
any and all suggestions/scoldings appreciated.

hot_rod

Gosh, pup

You might be coming at it from the wrong end. In my opinion those instantanous units are best left to the function they were designed. DHW production, period. You might be better off with a regular boiler if you need high temperature for emmitters and DHW production.

Scabbing a plate HX and pumps gets complicated and you still need storage?

The tankless units all suffer from the limiting flow through those minute HX tubes issue. Buying a 150,000 input and only being able to reap 60,000 for heat, with a monster high head pump, always strikes me as an odd approch. What, really, are the advantages to trying to making a tankless instantanous think it can behave like a boiler?

Keep shopping, I feel there are much better options out there.

hot rod

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kevin coppinger_4

well...

speaking for me notHR.....look into a Munchkin by HTP or if cost in not an issue a Viessman vitodens. Another option would be the Weil-Mclain Ultra. All are condensing.All have companion indirects from their respective mfgs. kpc

hot_rod

A boiler whisperer!

It depends on the application, zones, total load, smallest load, space, venting, mounting needs, etc, etc.

I have been pleased with the MZ in my shop, the Munchkin with the latedt control may be a great fit. To soon to tell on the Ultra, haven't messed with one yet, treat the aluminum fairly and it should be fine.

I've heard nothing but praise regarding the Viessmann Vito Sarducci, or whatever it's called Certainly the highest quality, and well supported.

I have a bunch of Polarises in with great luck, sometimes the volume is a good thing to have with micro zoning. You get condensing and buffer in one package. They have more sizes and upgraded controls out, now.

I feel even over 140F operating temperature, the condensing equipment has a bit of an efficiency edge. If nothing else the beefier insulation and lower mass helps the standby loss.

Wish the Americian boiler manufactures would upgrade that toilet paper thickness insulation the use on their cast boilers. How much could that cost??

Overheated mechanical room are becoming a big issue as the rooms sizes shrink and the buildings get tightened up.

Suppose the US boiler manufactures could sell an upscale boiler? One similar to the German in terms of quality of construction, heavy insulation, quality jacketing, nicely assembled, including labels that are put on straight Most come out of the crate looking like they were thrown together by "get it done and out the door quick" methods. Or is it just me?

hot rod

Joe_13

Just a HO's opinion on the Veissmann

In a million $+ home I can see the value of these high end systems. But for the average home owner does it make economical sense? Now a days I don't think people stay in homes for 20 years to recoup the cost. Sure you want a dependable system that's enegy efficent. but will a buyer give me 10 Grand more for my home because it has a Veissmann over a top of the line Burnham or Crown?

Dr. Heat

If you interested you might check out the hydronic heart with it you can use any boiler you want from fully condensing to standard cast iron we've spec and used it in many applications from 1mil$ to simple trac homes I also like the ultra boiler made with care here in the U.S.A.

August Hasz, Resource Engineering Group

NY Thermal Trinity Boiler

Another lower cost condensing boiler is the NY Thermal Trinity. They are fully modulating and around 92% AFUE (similar to the Munchkin, Ultra etc.) We consider them "the poor man's Viessman". The T150 (150 MBtu peak output) has a list price of around $1500. Simpler controls then Viess., but about 1/3 the cost and pretty competitive with the standard boilers. I think they are a very sensible upgrade from non-condensing options.