Pinnacle Dilema!

Jamie_6

I am bidding a small heating job and the home owner is requesting a pinnacle! The problem is, I did a load on the house and a few zones are less then 10,000 Btu’s and the whole house requires the 140,000 Btu model. I am worried because I have read that the boiler will short cycle when these smaller load zones call.

The home owner may never know that the boiler is doing this but I really think it will be beating itself up! What would you guys do? Push the Pinnacle or maybe tell her about the MI series and roll that extra $$$ into some heated bathroom floors?


Pompetti Heating & Air Conditioning, Inc.
www.PompettiHVAC.com

Steve Eayrs

Is the whole house load of

140mbtu, the combined heat and dhw load? Or just the house heat load?
If its both combined, size the boiler according the largest of the two loads, and run the dhw on priority.
If the 140mbtu is just the heat load, I would not be too concerned about a couple smaller 10mbtu zones. When its warmer out the boiler is way too big regardless of the size of the zones, as theres not enough delta T to suck the heat out of it anyway.
How about outdoor reset? With the right controls (tekmar is one brand)you can still get nice long burn cycles, since its does what they call "optimize the burner run cycle". Another way of saying this is it brings the boiler up to the a high limit, and bypass's the set point the outdoor would like to stop at, and then allow the boiler to cool off to 10-20 deg. cooler, than what the outdoor setback is calling for, before firing up again. The limits to how cool the boiler can run always depends on the boiler you are using, and the min. boiler temp. on the control is set accordingly. When dhw priority kicks in it bypass's the outdoor and runs hot until satified.
Not a fix-all but sure better, and more efficient too.
Steve

[Deleted User]

Pinnacle Pickle...

Hi Jamie,

Can you say buffering tank?

Can you say Munchkin with the Vision 1 adder?

I'm glad to see you are concerned with the short cycle issue, and rightfully so. If you do an outdoor reset (not recommended) the boiler will short cycle because it has one set point to focus upon and modulate around. It will always do this in high gear, modulating just before it reaches its fixed set point. If she is convinced that she likes this little boiler, introduce her to it's more intelligent clone, the Munchkin. Modify the lil bugger with the Vision 1 adapter and you have the best thing going on the market today as it pertains to modulatin' boilers with outdoor reset. The only thing better is probably outside of her budget, which would be the Viessmann Vitodens, but then again you won't know unless you ask...

Good luck, and let us know what happens.

ME

Mike Lampkin

Vision 1 Adder


HI Mark,

Could you please tell us more about the Vision 1 Adder.
Is it an upgrade to the Munchkin?

Thanks,
M.L.

[Deleted User]

You must be Vision 1 certified...

in order to get this adder. Talk to your rep.

ME

munchkin-man

The Pinacle dose not offer Vision one

You would have to find a different way to control modulation for a zone that has a btu rating that is lower than the lowest modulation point of the boiler. The use of a buffer tank would be the way to go in your case when using the Pinacle. This would use up the extra btu's generated by the boiler when needed.

George @ Dynamic Plumbing

Another way to prevent the short cycling of the boiler

Is to pipe the small load thru the indierct water heater's boiler loop. Take you small load supply from the boiler return side of the indirect and return to the supply side. You must install a couple of flow checks, but it works great. In this way you 'rob' heat from the indirect and when the idirect water temp drops to activate the boiler you definitly have a load that makes the boiler work efficiently. We have successfully used this arrangement with boilers nearing 300,000 with loads as small as 4,000 without any short cycling.
We have even taken loads as large as 45,000 and handled them in this manner.
A consideration would be your load temperature requirements for this to work well. The maximum temperature in the smaller load that we've delivered in this manner is @135F.
Hope this helps, any thoughts or questions just e-mail.
Good luck!!

john wood

Make the small zones \"dumb\"

By dumb, I mean do not connect the end switch of the zone valve to TT on the boiler. This way, the only time that the boiler fires is when you have a larger zone calling, or perhaps series wire the endswitch on two small zones so that just in case the two small zones call together and not a larger zone, the boiler will fire and not short cycle.

First choice would be a buffer tank if budget will allow. HTP makes a nice short 20 gal stainless one for just such stuff as this!

Jamie_6

Thank U

Thank you all for the good ideas! I taged them on my computer so I can review them again before I talk to our customer. I am in the process of learning more about the Munchkin and its Vision Card. We are know waiting for some literature on it so we can truely understand what it does.