Thermostat recommend with swing/hysteresis adjustment

[ARS]

Hi,

I have been learning about my Peerless MI-06 boiler and this forum has been an amazing resource - thank you. From what I have gathered here, is that it is overkill for our small house even though it is all brick with poor windows/insulation. I recently replaced the aquastat with a hydrostat for more adjustment - higher set point and eco mode to see if it will save a little money on gas.

We have a old lux500 thermostat and it does not seem to have swing adjustment like newer lux models. Our house starts to feel cold due to brick walls once the radiators cool and our thermostat waits about 1 degree too long before kicking in and so it 'feels' cold before comfortable again. Seems that if I can get a few more cycles it might stay comfortable longer. I know this because I can kick up a degree to cycle to take out chill then turn back down.

Do you recommend a thermostat that would play well with hydrostat?

Any recommended settings that work well with brick homes for this setup?

Thanks,
Anthony

 

[Fitter30]

Are u using outdoor reset? Small house 175k btu input? Sq. Ft. of house? What are your heat emitters- cast radiators? What's the run time at your coldest temp and boiler water temp? Excel offers a energy audit with a blower door test for $150. $600 value. However, most modern thermostats work a bit differently using an algorithm (like TPI) to give more precise control, or they vary the flow temperature from the boiler instead, to maintain a steady room temperature (weather compensation or load compensation. Some its cycle rate.

Xcel Energy

co.my.xcelenergy.com

 

[Sponsor]

 

[ARS]

I am not using outdoor reset via the optional hydrostat temp sensor.

House is 2500 sqft - half is the first floor and other half walk out basement.

Radiators are original 1940 cast iron single zone. I set the boiler to 200F max from its original 190.
I have been working on sealing the air leaks - mainly in ceiling - recessed lights etc. There is definitely a lot of work to do to improve the homes sealing and attic insulation but have replaced basement windows so far.

With the data I am collecting before the new hydrostat the cold start runs about 30 minutes to heat up before it starts to cycle the flame about every 10 minutes until thermostat is satisfied.

 

[Fitter30]

I am not using outdoor reset via the optional hydrostat temp sensor.

House is 2500 sqft - half is the first floor and other half walk out basement.

Radiators are original 1940 cast iron single zone. I set the boiler to 200F max from its original 190.
I have been working on sealing the air leaks - mainly in ceiling - recessed lights etc. There is definitely a lot of work to do to improve the homes sealing and attic insulation but have replaced basement windows so far.

With the data I am collecting before the new hydrostat the cold start runs about 30 minutes to heat up before it starts to cycle the flame about every 10 minutes until thermostat is satisfied.

What are the water temps in and out of the boiler? Boilers don't like to cycle they use more fuel cycling. Never heard of a hydrostat see it's using thermostat cycling to reset water temp. Which model hydro do u have? Water temp sensor where is it mounted?

 

[ARS]

The inlet temp is 127 and outlet is 136 - this was before I raised the temp from 190f to 200. The hydrostat is temp sensor is in well and the inlet/outlet thermocouples are on the pipes right next to boiler.

The hydrostat 3200+ has a eco mode setting that tests load by heating up to a lower set point(similar to outdoor reset) and test to see if that will reach the thermostat set point. If not it raises temp again and test. It keeps doing this up to the 200f set point. The theory is it saves gas by not heating to full 200f on cold start if house does not require it. There is a non eco mode but it does not use 'reset' approach. It just goes right to set point. There is an adjustment on delta so you can set to 10/20/30 degrees so it would go to set point and drop by 10-30 degrees depending on setting.

I just don't know yet if eco mode is causing more problems in terms of comfort and i should set a larger delta and just heat up to set point. I definitely know that thermostat waits to long to call for heat so everything cools down to a fresh cold start which seem like that is not optimal.

 

[Fitter30]

Hydrostat sensors insulated and how are they attached to the pipe ? If your running that cool return at least 135° i like 140° under these temps the boiler can be condensing, burner and flue rust cast sections of the boiler can crack and it's hard on the refractory. Your moving to much water through the boiler/ system 20° temp differential through boiler is standard design. Lux thermostat can change the temp swing. Any control settings baby steps should be taken. Don't change more than one setting and write down what was changed. Let it go at least a few hours.

 

[ARS]

They hydrostat sensor inserts into the same old aquastat well and has thermal paste.

I confirmed again with thermocouple and I am seeing 10-12 degrees drop between outlet/return.

The system has a taco pump 007-f5 and 1" loop. If I reduced flow rate with the current boiler, would that increase cycling?

 

[Fitter30]

It's 9°td post 5. Close the discharge of pump till it gets to close to the 20°across the boiler. Slower the water the more heat will come out of the water. Here's a chart how at different temp differences the btu ratings cast radiators. Having one zone I'm hoping not to short a radiator of water. Hydrostat is probably set up for 10° differential with trying to shorten the swing. Baby steps one change at a time.

Cast Iron Radiators Ltd

Delta T and Heat Output explained When selecting your radiators you will need to work with your plumber to determine the heat requirements of your

www.castironradiators.ltd.uk