Ideal Icos HE18 Frost Stat Issue

[northie]

Hoping someone on the board can help me with this issue - to which I am sure the answer is staring me in the face...

Problem

Our heating and hot water work absolutely fine on their schedule or manual boost, but...

When the temperature drops each night it triggers the frost stat and causes our boiler to fire up (correctly and by design) however instead of heating the pipes and turning off it is making a loud gurgling / banging noise (maybe kettling if I knew exactly what that noise was) which wakes the whole house up. I've been putting off sorting this because it didn't happen through the Summer and its fairly easy to knock off (see below), but now it's getting on everyone's nerves. I am assuming the noise is caused because the water is not passing through the boiler correctly under an active frost stat and therefore heats to the point steam is created and pressure in the boiler builds.

Specifics on My Install

• Boiler is an Ideal Icos HE18 located in an integral garage.
• Drayton PTS1 and RTS3 stats.
• Exposed flow and return which disappear into the roof space.
• As far as I understand this is an S-Plan setup in a 2007 home.
• Conventional boiler with hot water tank in an upstairs airing cupboard and header tank in the loft.
• Tank has previously been replaced so likely to have been maintenance on pipes and electrics.
• Honeywell and Range valves for radiators and hot water respectively.
• Boiler has failed 3 times needing new PCB on 2 occasions.
• Have installed Hive home heating controls - replacing programmer and leaving the internal room stat in place but set to max - i.e. Hive stat has control when heating on.
• Water in the area is known to be hard.

What I've tried

• When the issue happens if I boost the hot water for an hour on the Hive app the banging stops.
• Checked the 2-Way valves open and close when the heating or hot water are on.
• Condensate trap has been cleaned multiple times and makes no difference.
• Frost stat was attached to flow pipe but I've moved it to return pipe based on manual recommendations for the stat and the boiler.
• Frost stat was set to 55 degrees and this has now been adjusted to 25 degrees based on manual and recommendations.
• I've tried leaving the Honeywell 2 way valve for radiators manually open so water is able to flow.

None of this has made a difference however I did notice since changing the frost stat temp down to 25 degrees the banging doesn't last as long - which makes sense as the heat being produced by the boiler would convect/conduct from its location underneath the flow and return pipes and the jump from 5 to 25 degrees isn't huge.

Current Thoughts

• Could it be the pump isn't pushing the water round the system when the frost stat fires the boiler? How would I check this?
• Could it be the installation of the Hive was done incorrectly and somehow breaks the circuit for the pump / valve to operate when the frost stat fires the boiler?

I'm up to my neck in uni work at the moment (as a mature student) so don't really have a lot of time to sort this, but the boiler is keeping me awake at night - any help greatly appreciated.

Sure lots of the above will not be perfect understanding or terminology and all feedback is welcome

Thanks, John

 

[Jajodu]

If the boiler fires up on the frost stat and both 2 way valves are closed then unless you have a bypass valve there's nowhere for the water to go to lose heat, hence the boiler kettles. Can you find the bypass valve and check whether it's sufficiently open?

 

[northie]

I haven’t managed to locate a bypass valve. But last night I did move the radiator valve from automatic to manual / open and we still had the same noises. If my understanding is correct shouldn’t that have allowed the water to flow round the rads (assuming pump kicks in)?

 

[Jajodu]

Not unless the zone valve is open. Otherwise it won't have any effect.

 

[northie]

Yes when I say radiator valve from automatic to open I mean the zone valve that controls the flow from boiler into the radiators.

 

[northie]

After a bit of Googling of bypass valves in my dinner break I think I might have found it. Between the pump and the 2x zone valves I found a 3rd pipe off which joins to the return pipe coming out of the hot water tank. On that pipe is the valve below, it’s closed currently which is clearly wrong, but can someone tell me if it’s a pressure valve and is there a specific way to set it?

Still a little confused because if this being closed is the cause I’d have expected leaving the rad zone valve open last night to have also seen me through the night without any banging.

 

[ianmcd]

The frost stat when operating, should open the CH zone valve and power the pump, if this si not happening, it is either wired wrongly or you have something set up wrong, what temp is the frost stat set to and the pipe stat

 

[Harry Bloomfield]

A frost stat is normally placed in the coldest part of the house, where any parts of the heating system is located, set at 5C and wired in parallel with the room stat. That way, valve will be caused to open, pump started and boiler will run. It sounds as if your stat is wired up just to call for heat from the boiler, which will prevent the boiler freezing, but not the rest of the system.

 

[northie]

Frost stat (RTS3) sat at side of boiler is set to 5 degrees and pipe stat (PTS1) is on the return pipe and set to 25 degrees.

Last night I had the CH zone valve set to open/manual and in the middle of the night the frost stat fired the boiler and I still got the banging. There are 17 radiators in the house and all are fitted with TRVs except a small on by the front door and a larger one in the dining room which never seems to get very warm.

This bypass valve looks to be a standard gate valve and it is closed. Does it need to be opened and if so how much?

 

[northie]

Thank you all for the replies so far

 

[polesapart]

Could it be the pump isn't pushing the water round the system when the frost stat fires the boiler?

Yes, if wired directly to the boiler.
You need to wire the pipestat /froststat to one or other of the zone valve brown wires at the wiring centre.

The Icos HE has no boiler run-on i.e. the pump is not controlled by the boiler PCB

 

[Harry Bloomfield]

The Icos HE has no boiler run-on i.e. the pump is not controlled by the boiler PCB

They also suffer from overheated, burned and shorted wiring loom, which runs up the rear side of the boiler to the fan, between boiler and wall, producing a fan failure fault code.

 

[oldbutnotdead]

As others, when the frost stat is active does it trigger one or both of the zone valves (and thus the pump as well as the boiler). How to check- when heating is off, adjust frost stat setting til it triggers, check pump is running and valves are being driven open (no resistance on manual lever on the Honeywell).
By the way, if you latch a Honeywell 2 port valve open, next time the valve motor is activated it'll unlatch it.

 

[northie]

By the way, if you latch a Honeywell 2 port valve open, next time the valve motor is activated it'll unlatch it.

Aaah didn’t know that and did turn the heating back on through Hive after I finished playing with it last night.

So I’ve opened the bypass valve half way and turned the frost stat up to 10 degrees so it clicks and removed the stat off the pipe so the residual heat in the pipe was no longer shutting it off. Boiler fired up in frost protect mode and within a couple of mins I can feel substantial increase in heat on the return pipe. Suggests the pump is running ok. Difficult to be in garage and in airing cupboard at same time and if I ask the wife to lend a hand I’ll get loads of false positive results.

So I know CH zone valve is working and it’s highly probably it wasn’t open through the night manually. Would the design always be that this valve opens on frost protect or would some installs rely on the bypass. It would seem to me it’s functionally the same thing but surely less efficient to push water through all the radiators rather than round a small loop to provide heat in the 2 small sections of exposed pipe in the garage.

I guess what I’m asking is if I put it back together and tonight it doesn’t wake me up can I leave it at that or do I need to pursue the zone valve opening under frost protection conditions?

 

[ianmcd]

If wired correctly, and the zone valve isnt opening, then the pump wont be running