Low mass boiler temps

Joe_13

I'm looking to get a Crown Freeport CT boiler and megastor horizontal indirect DHW tank for my 3 zones of BB. The Tekmar 260 looks like the best controls for DHW priority and offers heat purge back into the tank after heat up. (just like an EK System2000). I don't want to set up mixing to keep it simple. The 260 provides outdoor reset I believe. My question is can the boiler truely shutdown and allow to cool off if the DHW tank and outdoor temps don't call for heat (summer time), or will the boiler still need to maintain a minimum temp to prevent thermal shock or to be able to quickly provide temp recovery when hot water demand comes on. I would think a low mass boiler would only need a few minutes to come back up to 160 degrees. Would a 260 be able to keep the boiler at 160 degrees for most of the winter and maybe go up to 180 on the colder days?

Al Letellier

low mass

Yes to all your questions about the Tekmar...it's an excellent control. As too the boiler, consult the manufacturer. Some require minimum temp to avoid thermal shock and condensing. I know of only a couple of boiler that are billed as "built to hancle thermal shock", but I don't know about Crown. They may not warranty against this type of damage.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

kevin

how big........

are the baseboard loops? Thermal shock, I thought was more like having a hot boiler and then dumping a large load into it. starting off cold and then dumping a start up load shoudn't crack it...kpc

Mike Lampkin

Thermal shock


Hi Joe,

You might want to look into using a 3-way valve from
Danfoss which is called the "Thermic Bypass Valve". You
can use this valve to protect your boiler from the cold
return temperatures coming back to the boiler. The TV
will not open until the return is at a certain temperature.
Check with your Danfoss rep. Good Luck.
M.L.

Boilerpro_3

Shock can happen 2 ways

Cold water into hot boiler and Hot water into cold boiler. In this case hot water out of DHW indirect into cold boiler. Other real common occurance is with stage fired boilers. System is at temp and then load increases so another boiler is fired and the pump on that boiler turned on. Hot system water enters cold boiler at full flow and OUCH!

Boilerpro

Lee Ensminger

Crown Freeport Boiler

The application you are cosidering with a crown Freeport boiler, a horizontal Mega-Stor and 3 zones of BB is a good application for the Freeport.

It is a low water content boiler that is designed so that it does not have to maintain temperature. When there is a call for heat it will quickly come up to the operating temperature required for the system.

You should also experience no problems with thermal shock on this application. Since thermal shock is more likely to occur when you have a hot boiler and you introduce cold water directly to the boier. I do not think this will be the case in your application.

If you have any questions about the Freeport or the Mega-Stror please contact us.

Lee Ensminger
Crown Boiler

heatboy

Technically..........

The Freeport would not be considered a "low mass" boiler. While it is smaller than most cast boilers, there is quite a bit of weight to it. Because of it's superior design, it's the only "American" oil-fired boiler I use. As far as allowing it to cool, it will take some time to do that. There is very little off cycle loss up the chimney due to it's three pass design. Running fin-tube baseboard, with it's small amount of water, will not do any appreciable harm to the boiler if used in a cold start application. I may be incorrect, but with Tekmar controls once it comes out of WWS, it cycles at whatever minimum temperature the control is dial in at. So this would mitigate any of your concerns anyway. If I am mistaken on this, I am sure someone will correct me.

hb

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Joe_13

Thanks for all the replies

Thanks Lee and everyone else. Crown's product line seemed like a great alternative to Buderus/Viessman products at a lower cost, I hope. The Tekmar controls look like they give you the same high-tech functions from an independent 3rd party. Would a single circulator be able to service the DHW tank and 3 zones of BB (about 60ft each) or is a tank normally put on a seperate circulator? The 260 looks like you can get a version to switch circulator or relays on zone valves but not both. Does a 260 have boiler/DHW tank temp sensors or does it get triggered from the aqua stats?

Steve Eayrs

My opinion is

that Tekmar is easier to wire, when switching pumps. I would use a seperate pump for the dhw at a min. and figure the baseboard pump(s) based on flow needed there. A seperate dhw pump makes running dhw on priority a little easier.
Also sounds like you like the control method of the system 2000, wondering why you don't just go with their system. By the time you add the boiler, tekmar, dhw and all together the EK boiler would most likely be the better deal, and I think they work great for dhw and baseboards.

Steve

Lee Ensminger

Tank circulator

In order to get the rated performance of the tank it is necessary to provide the specified flow rate and available head to the indirect. We find that this is best achieved when you use an individual circulator for the tank. As for the BB I will leave that decision to your contractor.

Lee
Crown Boiler

Joe_13

System2000 issues

Steve:
While I liked the System2000 Frontier (boiler stacked over a 40gal low-boy tank) I had a few issues: One rough price quote was rather high. Plus the EK-1 boiler is top venting, when stacked, this puts the flue at over 6ft high, higher then the base entry of my chimney. Also the System2000 has a 4" flue, probably requiring me to line the chimney with a very expensive liner since it runs so cool.
The low-boy is only 40gal and they use a heat exchanger instead of a coil in the tank.

The Freeport has rear venting like the G115 and Vitola boilers and a 7" flue. Lee can confirm, I assume the Freeport runs a cooler exhaust but is still at least 300 degrees keeping the condensation down. I was also told that Crown will be comming out with a 53gal horizontal tank which is the perfect size that I'm looking for.