Replace Honeywell L8148a with Hydrostat 3250


Old 09-24-16, 10:02 AM
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Replace Honeywell L8148a with Hydrostat 3250

I have been reading posts about the 8148 relay failing by solder cracking and am pretty sure That is exactly my problem.

My system was not making hot water and I discovered the remote HW tank circulator was working and the boiler was firing to settings but the main circulator was not coming on for HW or radiation calls for heat.

I hooked a separate 120V to the main circulator [disconnected 8148 at circulator] and voila !hot water and main circulator function.Luckily I have a bypass to my HW heat exchanger that is always partially open so no chance of killing circulator[I hope?]

My aquastat is so poorly placed that it is a major PITA to dewire it to allow me to resolder the relay connections. It doesn't help that it is on a 20A circuit and has 12 gauge wires.

I am considering replacing the 8148 with a Hydrolevel 3250 plus for the main reason that it can be mounted remotely [and hoping for some predictive/thermal logic savings] I have seen at least one post complaining of catastrophic failure of the 3250[spraying steam/water when it heated over limit. I do have a separate overlimit safety,I assume I can keep it ]

Anyone [looking at you NJT] think this might be worth it?

My system

LAARS D-MAX [steel,low volume boiler operated cold start,direct vented]
TACO ZVC 406 zone valve controller
Remote HW tank with bronze circulator
TACO mixing valves supplying in floor radiantand towel bars,first floor
Baseboards on second floor
I designed/built this system myself to approximate a System 2000 [without their control board or prices]
I am in upstate NY

Thanks for any advice
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Old 09-24-16, 10:54 AM
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Welcome to the forums.

NJT has left the board.
On the surface that Hydrolevel looks like a good replacement. Since I haven't worked with that piece I can't offer any opinions but another member should be able to add some info.

I do have a separate overlimit safety,I assume I can keep it
I definitely recommend keeping it in the system.
Old 09-24-16, 10:58 AM
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I have had 8148s (and 8124s) fail on me; but it's usually been the points or contacts that got burnt or oxidized or corroded, and I bought myself some time by filing them to achieve a more serious contact. They've usually died on me completely when the electro-magnet winding burned/melted. I guess Sid Harvey re-builds them by replacing that relay.

I've never had the circuit board solder crack or melt; but I guess that is worth checking out.

Over the past 10 years, I have relied on a digital Honeywell L7224U and haven't had any such issues.

My thought is that I'd first try to clean up the contacts before attacking the circuit board.
Old 09-25-16, 11:35 AM
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I've been using the 3250 for several years with no problems. I have heard of others with trouble though. Good luck, Steve

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