We're in California where we prehaps will only use our hysronic  radient floor heat 3 or 4 months out of the year. I have not yet selected a boiler and controls yet. Has anyone used the Peerless® Pinnacle® ? Hear there is a $1500 rebate going on.

Also can one use this as a tankless for the house water,  how would we separate the house water from the floor heat sysem with one boiler ?

Distributor suggestions on where to buy it and controls?

Thanks Guys!  John

The Pinnacle has a good reputation so far- I've yet to hear of any design issues unique to that line.

The most common way of using a modulating-condensing (mod-con) boiler for domestic hot water (DHW) use is by adding an indirect-fired tank as separate zone.

But using a (much cheaper) plate-type heat exchanger can work if the instantaneous output of the mod-con is high enough to keep up. The Pinnacle T50 has only about 1/4 the output of the typical whole-house tankless. Unless you have a 150KBTU/H+ boiler, you'll have issues trying to run the DHW off a simple heat exchanger. It's also not very efficient when used that way due to fixed losses from flue purges at every firing, whether you just drew a quart to wash your hands (resulting in less than 50% efficiency) or filled a 50gallon soaking tub (resulting in greater than 90% efficiency.) High efficiency front-loading clothes washers will add numerous short cycles as well as hand-washing.

For somewhat more money, going with a "reverse indirect" (eg. TurboMax, ErgoMax) as the DHW heat exchanger, plumbed as a buffer tank for the heating system saves cycling wear & tear on the Pinnacle but trades giving up few percent of condensing efficiency against gaining a few percent in reduced cycling losses. The crossover is dependent on the tank storage temp as well as plumbing & control design issues- (let a pro do the math), but if you keep the storage temp 120-130F you'll never drop below ~88% combustion efficiency, and the minimum burn cycles will be reasonably long, never "seeing" the short bursts of hand-washing, etc. you'd get in normal hot water use that would KILL the efficiency of the boiler (and wear it out) by excessive short cycling. This configuration is an in-between- it gives you some reserve-capacity on the hot-water front, so the undersized boiler doesn't really have to keep up, only catch up. But with low storage temps it's not buffering as much reserve heat for "endless shower" teenagers. (You can always bump up the storage temp if you find you don't have sufficient HW capacity, but it'll be at the expense of condensing efficiency.)

This is WAY cheaper and more efficient than adding a separate tankless to handle DHW loads. It's also more efficient (but more expensive) than going with separate standalone tank. (Generic standalone tanks have atrocious standby losses, and low to moderate combustion efficiency). But it's also more expensive than a standard-indirect run as a separate zone. Whether it's more efficient than a standard-indirect overall depends on the heating system- if it's a micro-zoned staple-up radiant system it probably is. If it's a monolithic single-zone gypcrete/concrete slab, probably not. A good heating system designer would be able to tell you on which side of the fence it falls.

Don't go buying an oversized Pinnacle just to meet the peak DHW load- it'll be one of the least-efficient ways to go (unless you similarly oversize the buffer tank, that is, making it the most EXPENSIVE way to go. :-) ) Do a real Manual-J type heat loss analysis on the place (odds are you'll be at the smallest end of any vendors' mod-con offering), buy the right-sized boiler for heating, and a sufficiently sized indirect-tank to handle the DHW loads. Peak DHW loads are often (usually?) many times the peak space heating load, but they're intermittent, with a fairly low AVERAGE load (smaller than the output of the tiniest mod-cons.)

(I forgot to add): IIRC Peerless has controls for the Pinnacle for optimizing efficiency when maintaining buffer tanks (like reverse-indirects), making it a better choice than some others if that's the system topology you go with. Most mod-cons (the Pinnacle too) come with outdoor-reset (modulating the firing in response to outdoor temperatures), but few other options.