Some advice for an overheating Aquatherm..............

Guys,

First post but 7yr Aqua-Therm 145 owner......here's what I need help with..... Boiler is outside in shed, approx 90ft from house, down hill (slight). With outside temps up and down this winter, I've been having "boiler over" issues this past year, after just running with straight water, instead of 50% glycol. Have been setting aquastat between 160-170 to compensate for ambient temps.

Have a stacked plate exchanger at inside hydronic oil boiler, and use the existing baseboard loop as a constant dump zone with constant running taco 007.

Temp. relief valve has been going off and would like to create a expansion/dump zone at boiler site....or believe that's what I need to do? If heat isn't being used over period of time, it just gets to be too much, no matter what I set aquastat to.

What do you need from me to help figure this out? I've read a bunch of articles and have fine tuned this system over past 4yrs (inside and outside).....but would like to fix this.

My 145's capacity is 48 gal......and have about a 90ft run of 1" pex loop. Pressure relief (30 lb) and temp relief valves (210 blow off) are in place.....

Can I just put a tank (how big if yes?) above highest pipe point, remove temp relief valve, and pipe up to that to let water expand up there and then let gravity feed back down? Or???

Thanks for your time to look at this! I appreciate any help possible.

ATV.....I have to verify the temp blow off valve amount.....I assumed 210, but haven't been there (when happening) to see actual blow off temp. That's the only valve I haven't replaced since new, and would say that it's blown off approx. 10 times in 7 yrs.

I also have the aquastat at 165 with a 12 diff......at least today I do. Have had it around 160 to 170 for most part.....but last year (and yrs before) when antifreeze was in, I never ran it below 180 with same diff.

Pressure valve has been replaced and never blows unless overfilled.

This year was the first to run just water, because of cost of antifreeze and blow off issue, then wait time to cool off to fill boiler back up.....so just did water (manual fill inside house tied into return loop) and did notice that it was hotter and held temp better, but again, came up in temp faster too.

Bob....It's the stock bladder tank that came with setup (normal size for most residential boilers that I've seen)......I'll verify it's not waterlogged, and haven't had pressure issues, so my assumption is a tired T/P valve, or just can shed the heat when I don't call for it in longer periods of time.

I just did a search for the Amtrol tanks you showed from their calc........man... they're expensive! I can see what you mean by mine being undersized! Unfortunately, that's where I have to usually make my things work, or go outside the box to use/adapt something for me.

Pat......I haven't replaced the gasket from new, so that may be helping the upper temps.

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I have a room in house that can't be heat satisfied, IE, 2 small wall rads, full wall of windows, older build and on slab with slate floor. This is where I also have a fireplace insert that I run also during winter. I have fine tuned the running of boiler and running of fireplace, by moving my single thermostat into my bedroom (was in hallway) and buffer that by shutting my bedroom door...........long periods of door shut and not calling for heat, puts me in that boiler over situation......this is where I'm looking for a long term solution for the boiler over issue.

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Maybe first I should replace the T/P valve and see if it's the main culprit? Is it anything special that can't obtained from parts house? IE, what are the specs for this Aqua-therm valve?

Thank you for taking the time to offer your help....I appreciate it.

WMaster........OK....I agree, I'll change that and the old T/P valve. I do remember it dripping at bottom of door when using damper wood, so it's been crushed down there at least.

Maple.............def. Temp valve issue......there's 2 relief valves and the one that's hot (after expelling water) is the Temp Relief.

I run this about 15 lbs when hot and don't have any issues with pressure....until long after it's been boiled over (if away or not seen for hours) and below circ. level.....besides smoldering wood/coals to keep temps up...bringing up the pressure over 30 lbs

Thanks

Bryant......it never sees 30 lbs until long (hrs) over boiled and can't circulate from temp relief valve removing enough water to stop circulating.....never in a normal heat cycle........15-17 max at full temp aquastat shut down.

I ordered new door and ash gaskets and new T/P valve....should be here by Thurs. Called buddy who sold this to me (10 yrs ago actually) and discussed these issues I've mentioned....his first suggestion was the door gasket too.....I'll advise sometime this weekend after replacing these gaskets and T/P valve.

Thanks for all of your help.

I ordered the door and ash gaskets, and a new T/P valve..........Aqua-Therm spck'd Cash Acme 210 deg. off x 80 lb off..............called buddy/dealer who sold me this (actually 10 yrs ago now!) and first thing he said was door gasket too!

I'll update after parts come in and I install (end of this weekend most likely).

Thanks guys for all your help