Beckett Aquasmart

[Naren Rao]

So my oil company showed up for the annual furnace tune-up yesterday. And this time I was ready for them with having gotten all the great knowledge gained on the forum here on heat loss, triple pass boiler, Intellicon HW+ etc.

So he threw me a curveball - In his opinion, the Honeywell aquastat 8148A is of the wrong type installed on my boiler. he said with no indirect tank attached, the boiler still maintains temperature, because of this specific aquastat, when it does not need to. He literally took the low limit to lowest setting 120 and let the Hi remain on 180. He suggested a triple aquastat (Beckett Aquasmart) and not Intellicon HW+ for oil savings after he heard how much oil I had burnt last season. The Aquasmart continually adjusts the Hi based on the heat calls rather Intellicon which only adjusts the diff. So folks do I install the Aquasmart. What does everyone here think. Also does this need a full drain of antifreeze in the 3 zones.

Feedback is appreciated. Thanks in advance

 

[KevinPrz]

I think you should post some pics and model of your boiler... I'm a dummy and will sit back and read the replies but from what I've learned here is 120 is too low for an oil burner and will reduce the life of the boiler from condensation.

 

[Sponsor]

 

[Dana]

Your contractor is simply wrong about how the Intellicon 3250 HW+ works. It does not adjust the differential, it purges heat from the boiler both at the beginning of a call for heat (down to whatever you program the low-limit to), then cuts the burner prior to the end of a call for heat based on the system behavior on prior burns- it "learns the system. From the manual:

The boiler aquastat has requested the burner to come on but the IntelliCon®-HW+ has sensed that there
is available heat which can be used without burning fuel. The burner will remain off and useful heat will be delivered from the boiler’s existing supply of residual heat.

That's the start of cycle heat purge.

You cannot program the differential or the high-limit with the Intellicon, but you can set the pre-purge time and a maximum hold off time, and the low limit temperature to purge to. The differential will be whatever you set the high-limit aquastat to, and the programmed low limit, and it won't intermittenly fire during calls for heat unless it actually hits the high limit, a which point it purges completely to your programmed low-limit.

As I recall from earlier threads yours is a hydro-air system, not radiators or baseboard. With a hydro-air system there is little benefit to having an automatic-adjusting the high limit, since it may end up causing the boiler to cycle on/off during the call for (which reduces efficiency), increases the amount of air-handler power use (due to the much longer cycles), but it will park the boiler at a lower temp at the end of a cycle for lower standby loss. The Beckett Aquasmart doesn't seem to have the same heat-purge features, but it allows you to program differentials. Those differentials are not infinite- if you set a low hi-limit it'll keep cycling, during calls for heat. From the manual:

The Heat Manager saves fuel by dynamically changing the
temperature high operating limit to the minimum
temperature necessary to meet the heating demand
---
The HeatManagerTM algorithm is designed to operate the
boiler at its lowest possible temperature while still
meeting the heating demand. By dynamically changing
the boiler temperature, it is designed to reduce the
energy used by the system without sacrificing comfort.

That is effectively an "outdoor reset" type function, which limits the distribution losses, but doesn't heat purge, and will ADD rather than reduce the number of burn cycles, and increase the power use. That can reap both comfort and fuel economy benefits with radiators while adding a bit of pumping power, but it still can short-cycle the boiler, taking back some of those benefits.

But hydronic pumping power is an order of magnitude lower than air handler power. Lowering the high-limit on a hydro-air system adds quite a bit to the electricity used- the fuel use dollar savings with that approach may be erased by the increase in the electricity bill.

My gut says the Intellicon has a better chance of saving fuel without a huge uptick in power use, and by having the higher high-limit, the air coming out of the registers will be at a higher temp during most of the cycle-it'll be more comfortable. The Beckett Aquasmart's approach is more appropriate for high-mass radiator systems, and may even be OK with low-mass fin-tube, but it's ill adapted to hydro-air.

 

[Naren Rao]

Thanks Dana for the detailed explanation. I just read the hydrolevel 3250plus model and bought it. It does have LWCO, heat manager, purge capabilities and a outdoor reset built in.

 

[Dana]

As long as you can turn off the outdoor reset (which buys you nothing with hydroair), and enable the heat purge functions, most economizers will work with hydro-air.

 

[Naren Rao]

Thanks Dana, The outdoor reset on the Hydrolevel 3250+ works only if the outdoor sensor is connected. It touts the following features:

For oil boilers it supports Cold Start or Warm Start operation. (Replaces the 8148 Aquastat which is not needed on my setup as there in no indirect water tank so reason to "maintain" Boiler temp). Provides enhanced condensing protection – reduces the potential for condensing, on a call for heat, this allows the boiler to heat to 125°F prior to energizing the circulator. Once activated, the control continues to monitor boiler temperature and interrupts the circulator if it drops below 115°F.

Thermal Targeting - will adjust boiler water temperature according to changes in heat load during non peak demand (Heat Manager)

Thermal Pre-Purge – Further enhances boiler efficiency by supplying latent heat, that may remain in the
boiler from a previous run cycle, to the heating zone requiring heat. The control activates the burner only
when it determines that the latent heat will not be adequate to satisfy the heating demand.

Outdoor Sensor automatically activates outdoor reset and warm weather shut-down functionality.
When the sensor is plugged into the control, the boiler reset methodology changes instantly from Thermal Targeting to Outdoor Reset, where the boiler temperature is governed by the temperature outside. The addition of the sensor also allows the control’s Warm Weather Shutdown feature to be activated. This feature prevents the boiler from supplying space heating when the outside temperature exceeds a selected level.

LWCO functionality automatically activated when installed with Electrowell

 

[Naren Rao]

Hi , am back

Got the 3250+ installed recently on a oversized peerless boiler. Had few questions

1) with thermal prepurge on, the burner does not kickin however as soon as temp is 169 (from 180)? the furnace kicks in ? 11 deg diff that's it ?

2) Eco setting at 3 (3 zone circulators) however have a total of 5 dampered zones (5 thermostats). Should Eco setting be 3 or 5.

Thanks