optomizing my Hydrostat 3250 Plus

[docbar99]

This is the system I had recently installed. It has a Riello burner with the 0.62 GPM nozzle. I have only about 67 ft of 2 in baseboard, so my system is oversized. The house is about 1000 sq ft and no one is home most of the day, so I keep my thermostat on 63 at all times..

If you see the picture below I have attached some sensors and a micro controller that logs data to google sheets and a cell phone app.
I have one attached to the hot water and one above the circulator. I also have a current probe that monitors when the burner is on.
I am not a hydronics guy and I am not sure about the plumbing.

Is the sensor above the circulator measuring the water going to the baseboard or the returning water?

If that sensor is monitoring the water going to the baseboard I am concerned that the water returning to the may be much colder and maybe bad for the system, condensation or other issues. I think part of the problem is that at 63 degrees setpoint, the baseboards rarely feel warm. The way the contractor setup the system it was short cycling as seen below:

In this plot data is collected every minute for 2000 readings in a 1.4 day cycle. This is a zoomed in plot of about 4 hours,
The setting was HL=180, LL=140, ECO=5 and the switch was set to Indirect which I found to be wrong because this is a tankless coil with no indirect water heater. Here the burner was only staying on for about 2 or 3 minutes.

After reading the Hydrostat manual and getting some advice from another forum I made some changes in the settings and switch.
The arrow shows when I made the change. The orange trace is hot water and the blue is the circulator water and grey is the burner on as detected by the current probe but represented as a digital output, on or off.

These changes helped with the short cycling as the on time is about 8-10 minutes.

This is the summary of a test I made a few days ago when it was a little colder outside.
I also have one sensor next to the thermostat and one outside.

Also- I am not sure if my circulator temperature sensor is the right place to make meaningful measurements.

I would still like to try some more settings, but would love to hear some suggestions.

 

[Fitter30]

Your sensors are not mounted correctly need to use a stainless hose clamp and insulated. Baseboard heat? Brand and model number of boiler?

 

[Sponsor]

 

[docbar99]

@Fitter30- Thanks for responding to my post. The sensors I use are general purpose and not designed to be mounted to pipes. Using a hose clamp is a much better idea, I will get some and install. I am just looking for a relitave temperature measurement to help me understand the behaviour of the Hydrostat 3250 plus.


Here is my boiler model

I have the Riello burner with the circled boiler. My baseboards have a 2 inch fin (aprox 67 feet installed )

As a beginner in hydronics, I am not totally sure about the piping. If you see the sensor I have above the circulator, is that the water going to the baseboards or the water returning from the baseboard?

 

[Fitter30]

Boiler is oversize for heating. Slant fin has 3/4" fin tube with a little larger fin @ 160°water 450btu per ft 67'= 30160 btu.

 

[docbar99]

Thanks for your reply. I did take your advice and mounted the sensors with hose clamps.

That sounds like a nice match for the boiler, but I am not planning to change the baseboards, just looking to optomize the settings on my Hydrostat.

As of now, I can only measure the temperature of the pipes and when the burner is drawing current. That is the feedback I can measure at this point. Basically I can compare the burner on time vs. the outside temperature to determine efficiency.

Let me know if you have any suggestions.

 

[Fitter30]

Boilers are most efficient running not short cycling.What was the nozzle size of the old boiler? Boiler had to cycle in the coldest weather.

 

[docbar99]

@Fitter30 - Thanks for your reply- I have no idea what size the old nozzle was, but the old burner was a Beckert, so I would imagine it had a larger nozzle. When I agreed to this configuration I wanted the slowest flow rate and according to the data sheet, I needed the Riello to get the 0.62GPH rate. After the install it seemed to be using allot of fuel and they came back and changed the nozzle. The technician said it was the wrong nozzle and it was also not adjusted, so he put in a smaller nozzle and adjusted it.

I then posted a question about the hydrostat settings on another forum and according to other experts, the settings were wrong for a tankless coil system.

Original settings:
HL=180, LL=140, ECO =5, Switch was on Indirect

Current settings: SW = Zone HL=170, LL=140, ECO=OFF, Pre-Purge OFF, Circ Hold_OFF=ON