Oil Burning Running but No Zones Active

OREGATO · 26-01-2019 04:24PM #1

Hi guys,

We have a Riello oil burner, it's about 10/15 years old. We have 3 zones in the house, upstairs, downstairs and hot water.

We've started to notice on occasion that the boiler is running however, none of the three zones are on. So we don't feel the heat in the hot water or anywhere in the house. Our thermostats are all turned off so there should be no reason why the oil burner is running at all. We have no schedule set up.

Can anyone give any suggestions at what to look at? I'm worried that the boiler is running but no zones have been activated.

Any help would be greatly appreciated.

Thanks,

O

Dakotabigone · 26-01-2019 04:26PM

Frost stat activated maybe.

jimf · 26-01-2019 04:47PM

motorised valve sticking or frost stat

Ak84 · 26-01-2019 04:50PM

Frost stat should be turning it on at about 4 degrees.
Does this seem right?

jimf · 26-01-2019 04:54PM

Ak84 wrote: »

Frost stat should be turning it on at about 4 degrees.
Does this seem right?

yes for boilers with built in stats

their non adjustable

Wearb · 26-01-2019 05:10PM

OREGATO wrote: »

Hi guys,

We have a Riello oil burner, it's about 10/15 years old. We have 3 zones in the house, upstairs, downstairs and hot water.

We've started to notice on occasion that the boiler is running however, none of the three zones are on. So we don't feel the heat in the hot water or anywhere in the house. Our thermostats are all turned off so there should be no reason why the oil burner is running at all. We have no schedule set up.

Can anyone give any suggestions at what to look at? I'm worried that the boiler is running but no zones have been activated.

Any help would be greatly appreciated.

Thanks,

O

Could be a stuck micro-switch on one of the zone valves.

OREGATO · 26-01-2019 05:19PM

Thanks for the quick replies.

I have 3 zone valves that look like this:

20171215_124730 by Pulsar_vzr, on Flickr

The lights are not on on any of them and there is no heat in any of the rads.

Is there any way I can check for the frost stat? It's not that cold outside at the moment so I doubt it should be kicking in?

Even now, when I go out to the boiler, I can hear it "humming" away, none of the zones are on and the rads and hot press are cold yet I've noticed the boiler kick in (steam from the exhaust pipe) but then it turns off but theres a constant humming sound - is this safe or should I unplug it?

Wearb · 26-01-2019 05:24PM

OREGATO wrote: »

Thanks for the quick replies.

I have 3 zone valves that look like this: 20171215_124730 by Pulsar_vzr, on Flickr

The lights are not on on any of them and there is no heat in any of the rads.

Is there any way I can check for the frost stat? It's not that cold outside at the moment so I doubt it should be kicking in?

Even now, when I go out to the boiler, I can hear it "humming" away, none of the zones are on and the rads and hot press are cold yet I've noticed the boiler kick in (steam from the exhaust pipe) but then it turns off but theres a constant humming sound - is this safe or should I unplug it?

When you say humming away, do you mean it’s doing just that and not firing up to flame, ie hot flue.

jimf · 26-01-2019 05:24PM

the humming is possibly the circulating pump which indicates the boiler is getting a signal for heat

but if no circuit is open and you don't have a bypass then the water cant circulate so boiler will only run for a very short period of time

the danger is your boiler could possibly trip its high limit stat which would need to be manually reset

OREGATO · 26-01-2019 05:27PM

Wearb wrote: »

When you say humming away, do you mean it’s doing just that and not firing up to flame, ie hot flue.

It is firing on intermittently for a few seconds then turning not firing.

When it is not firing, you can hear the boiler humming, sounds like the water is circulating or pumping?

I'm not sure how boilers work

, but I assume that if all thermostats are off, the boiler would be off, i.e the pump would not be going and there would be no humming sound off it.

I'm almost sure any other time I've checked the boiler, it's made zero noise, not even this humming I'm referring to

jimf · 26-01-2019 05:32PM

boiler running for very short period of time and then not

I think means boiler up to temp because no water can circulate when all valves are closed

sticking micro switch on motorised valve can cause this signal going to boiler but valve not activating

maybe valve itself is faulty

OREGATO · 26-01-2019 05:40PM

Is there any way I can check for a sticking micro switch on a motorised valve?

Wearb · 26-01-2019 05:57PM

OREGATO wrote: »

Is there any way I can check for a sticking micro switch on a motorised valve?

Yes. By using a multimeter at the wiring centre or junction box, depending on the wiring. You would need to be competent with electrical wiring to do this.

agusta · 26-01-2019 06:58PM

What make /model boiler, is it an outdoor heatpac boiler. First thing id look for is the frost stat and see if there is a frost stat.it will be located near the boiler

OREGATO · 26-01-2019 07:34PM

The boiler is an Riello RDB.

I went out to the boiler and turned on and off each zone, upstairs, hot water and downstairs. The last one I tried was the downstairs and once I turned it on and then off, the boiler finally stopped fully - I could not hear the pump and it was completely stopped.

Would this mean it's more than likely that it's one of the motorised valves at fault and possibly the downstairs one?

It appears to be intermittent because I tried to turn on and off each zone after that but now the boiler completely stops every time.

A mate of mine is an electrician who's going to take a look tomorrow. Hopefully he'll be able to test it with a multimeter - is there anything specific I could tell him to help?

The motorised valves I have are Sunvic, very similar to these - https://www.plumbingproducts.ie/motorised-valves-ireland/3150-sunvic-motorised-28mm-2-port-spring-return-valve-actuator.html is this potentially the part that is faulty?

Just so I understand the basics - Inside the house, there are heating controls, when I turn on the heating here for downstairs, it sends a signal to that motorised valve which then mechanically opens the pipe so that the hot water from the boiler gets circulated in that zone. When this happens, this motorised valve will also tell the boiler to turn on in order to heat the water - is this how it works?

So in essence, I could potentially have a motorised valve that is faulty, whereby, when I turn off that zone, it shuts that zone mechanically so no water passes into that pipe but perhaps it is not actually telling the boiler to stop firing. Can someone tell me that makes sense?

agusta · 26-01-2019 07:42PM

The time clock send a signal to the wall thermostat.if the thermostat is calling for heat it sends a live to the motorised valve.The motor in the valve turns and opens the valve and also makes a micro switch.the micro switch then connects the permanent live to the boiler/pump
A micro switch sticking means it doesnt return to the off position when the time clock is turned off.
It easier to diagnose the faulty motorised valve when it is actually in the stuck position

OREGATO · 26-01-2019 10:11PM

agusta wrote: »

The time clock send a signal to the wall thermostat.if the thermostat is calling for heat it sends a live to the motorised valve.The motor in the valve turns and opens the valve and also makes a micro switch.the micro switch then connects the permanent live to the boiler/pump
A micro switch sticking means it doesnt return to the off position when the time clock is turned off.
It easier to diagnose the faulty motorised valve when it is actually in the stuck position

Thanks,
When you say diagnose the faulty motorised valve, are you talking about the micro switch? The valves appear to be closing fine, except I know the upstairs did stick a few times, so when the valve was closed (light off) the upstairs was getting a bit of heat. Could this have an impact on the micro switch too?

agusta · 26-01-2019 10:35PM

OREGATO wrote: »

Thanks,
When you say diagnose the faulty motorised valve, are you talking about the micro switch? The valves appear to be closing fine, except I know the upstairs did stick a few times, so when the valve was closed (light off) the upstairs was getting a bit of heat. Could this have an impact on the micro switch too?

Yes a sticking motorised valve will have an impact on the micro switch.The next time the heating stays on you can check the upstairs motorised valve.Move the lever on the valve to manual and back to auto

OREGATO · 27-01-2019 06:03PM

Ok guys, here's an update.

It happened again this morning, had the downstairs and HW zones on this morning then turned them off but the boiler was still running.

My electrician couldn't come over but walked me through how to test the wires over the phone.

I was able to determine that when all the motorised valves are off, it is the downstairs valve that is sending power to the boiler. My electrician told me to remove this wire and tape it up for the time being so for now, if I want the downstairs on, I will have to have either the HW or upstairs zones activated before the boiler will turn on.

I just wanted to ask does the above sound right?

Also, this is a picture of the motorised valve, are replacements available that will be a straight swap? I would not like to have to tap into the plumbing if possible. The model is a Sunvic SZ2401, can I get a like for like replacement and where would be the best place in Dublin?

Here is a picture of one of them:

20171216_165858 by Pulsar_vzr, on Flickr

Here is a picture of the base plate which I do not want to change.

20171216_163914 by Pulsar_vzr, on Flickr

Any help would be greatly appreciated. Thanks again.

TheDriver · 27-01-2019 07:03PM

My plumber replaced one few months back with different brand, no pipe work changed.

agusta · 27-01-2019 11:29PM

How did you test the wires...,what colour wire did you disconnect,

OREGATO · 28-01-2019 06:48AM

agusta wrote: »

How did you test the wires...,what colour wire did you disconnect,

I used a phase tester. I disconnected the grey wire. Of all three grey wires, the one from the downstairs valve was showing power when all valves were supposed to be off.

Irish Steve · 28-01-2019 10:38PM

Looking at the valve body picture, the valve actuator does not look as if the motor closed the valve completely, which might be that the spring that closes the valve has become weak, or that the motor gears need some lubrication, so the spring can no longer provide the power to completely close the valve, and if the valve does not completely close, the switch will remain on.

I have similar valves here, and over a period of nearly 30 years, I've replaced 2 heads for similar reasons. There's not usually any plumbing involved if you can get the same head, but before changing the head, make sure that the valve itself is free moving, there will be a little resistance to turning, but if the valve itself is sticking, that can mean more work to replace the complete unit, it used to be possible to get replacement parts, but I haven't seen any now for a while.

In theory, hard water should not affect a valve of this sort unless there is a leak somewhere that's introducing new water to the system on a regular basis, the radiators and hot water circuits are a closed loop that should not lose any water, but if a leak happens, limescale can build up in the valve and cause problems, but that would be incredibly rare.

OREGATO · 05-02-2019 04:40PM

Hi guys,

Sorry for the late response but I thought I'd just post up and give an update.

I ended up switching out the motorised valve for a Danfoss version, didn't need to change the plate which was a relief.

It's been working fine since so I'm relieved it's got sorted.

Only difference between the Danfoss and the old Sunvic is the Danfoss doesn't have an LED or metal indicator to show that the valve is open/closed but it was also €65 cheaper than the Sunvic part.

Thanks again for all the help on this thread! Really appreciate it!

jimf · 05-02-2019 05:43PM

glad u got sorted

thanks for coming back it helps to know if we wer on the right track or not

this thread may help somebody else in the future

Fingers Mcginty · 09-02-2019 06:02PM

OREGATO wrote: »

Hi guys,

Sorry for the late response but I thought I'd just post up and give an update.

I ended up switching out the motorised valve for a Danfoss version, didn't need to change the plate which was a relief.

It's been working fine since so I'm relieved it's got sorted.

Only difference between the Danfoss and the old Sunvic is the Danfoss doesn't have an LED or metal indicator to show that the valve is open/closed but it was also €65 cheaper than the Sunvic part.

Thanks again for all the help on this thread! Really appreciate it!

You actually changed out the actuator

.
The valve is a bit trickier to change out.
I had a similar problem to you. The spring in the actuator got weak and was not strong enough to return the valve to the closed position hence providing power to the boiler. Glad you got sorted.

jimbobmalones · 11-09-2020 05:19PM

Hi all

Just have the same problem as OP - want to replace a Sunvik SZ 2401 actuater but not sure what alternative replacements will fit the base plate.

Any help appreciated

J

Oil Burning Running but No Zones Active

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