Worcester greenstar 28i junior anti-cycle plus by-pass valve.

[ericmark]

I have a problem which may be completely unrelated to boiler, however I have tried most things not to do with boiler so I need some help understanding the boiler so I can cure the problem.

So problem, a downstairs room is being used as a bedroom for my mother 92 and the radiator is about the furthest from boiler, because downstairs if the system is turned off at night, her room gets too cold, however left running overnight and her room is too warm, I want room at around 20°C when she goes to bed, dropping to around 17°C over night and back up to 20°C in the morning.

My wife and I live upstairs and also want a reasonable temperature, but it's the one downstairs room which is really important.

So we have a thermostat in the hall, with a rather large radiator and a TRV fitted, from the hall we have stairs, bedroom, living room, kitchen and wet room. Both wet room and kitchen heated with towel rails, plus electric under floor heating in the wet room, used on Friday night and Tuesday night only. The bedroom and living room both have eTRV's fitted, set to allow rooms to cool over night to 16°C and back to 19°C living room and 20°C bedroom in the morning.

However the rooms are not warming up fast enough in the morning, the whole central heating is set to switch off at 4 am and back on at 6:40 am with the eTRV changing at 6:30 am so boiler should start 10 minutes after the valves have opened, so in theory the two radiators should warm up in plenty of time. In practice however the rooms are not warming up quick enough.

Now my plan was assuming hot water from boiler at 6:30 am however if any anti-cycle software was to cause the boiler to be switching off again then that could be causing the radiators delay in heating, I note there is an external by-pass valve, but also it seems the boiler has an internal by-pass valve is this correct?

The hall radiator is throttled back on the lock shield valve to try to both delay it warming up and push more water through the bedroom radiator where the by-pass valve is fully open. The bedroom radiator is rarely very hot. The TRV on the hall radiator set to 2.5 is to stop the hall radiator getting too hot, the thermostat set to 17.5°C and a thermometer stuck to it shows 17.6 to 18.3°C when heating is running, don't really want hall any hotter, doors to all rooms are kept closed at night.

It would seem the radiator in the bedroom and living room are simply not getting enough hot water, the valves can be heard opening and closing, but often the radiators are only tepid, if the boiler is cycling then the hall radiator may heat up the hall thermostat before the other two rooms have had chance to get warm. Hall radiator is rather big, so once hot it takes a long time to cool again.

So can some one explain the anti-cycle software built into the boiler? One thought is a programmable wireless thermostat in the kitchen in parallel with the one in the hall, set to run 7 am to 9 am before we get up and use kitchen it would not be effected by cooking and could maybe be used to ensure boiler is running, already wired in and sitting in living room but set to frost only so not active.

 

[Agile]

It sounds as if you are yet another with too many controls which combine their effects to not do what you want.

A boiler only supplying a very small heating load will be forced to turn off when it's minimum heat output is too much. It will stay off for the duration of it's built in anticycle delay, usually about 3 minutes.

I have to say if the rest of the house does not need heat during the night and its only the min temperature in the 92 y.o. bedroom which is of concern then if it was mine then I would just use an electric heater to maintain the required minimum temperature of 17 C.

Tony

 

[Steelmasons]

If you're that concerned about your Mother i find it strange that you are wasting so much time on a Diy forum as opposed to paying for a professional to attend in order to sort all these non issues of yours out.

 

[ericmark]

It will stay off for the duration of it's built in anticycle delay, usually about 3 minutes.

I have to say if the rest of the house does not need heat during the night and its only the min temperature in the 92 y.o. bedroom which is of concern then if it was mine then I would just use an electric heater to maintain the required minimum temperature of 17 C.

Tony

That's the info I needed 3 minutes off. I will as an experiment set up a thermostat in kitchen to give morning boost, mother in rest bite at moment so I have time to play without it effecting her. Problem is normally we sleep upstairs and heat raises, so simply turning off the boiler upstairs does not cool that much, but mother is downstairs where it does cool quickly. OK I know a bungalow is downstairs bedrooms, but they don't have a staircase acting as a chimney taking heat away.

Your idea of an electric heater is good, if all else fails I will go down that route. The central heating will maintain the temperature, but will not boost the temperature back to daytime levels.

 

[ericmark]

The heating now seems to be working reasonable, not sure about living room eTRV it seems the radiator is still warm when the temperature is 1°C above set temperature, but wonder if just asking too much from the eTRV 1°C is not that much in grand scheme of things.

So I will admit my errors and say what I found.
1) I swapped the standard valve for a TRV on the hall radiator and failed to realise that was the valve being used as the lock shield valve, which resulted in staving the bedroom radiator and heating up the hall far too quickly. Once the remaining valve was throttled back, there was a marked improvement.
2) Connected with above, the off time for whole system and on time for whole system first thing in the morning was not long enough, increasing the times before 8 am where it is aimed to house warm again after the overnight heat reduction, plus adding the second thermostat to kitchen set to 20°C increases the early morning boiler run time, so for 2 hours 6 am to 8 am very unlikely the boiler is not running. The kitchen thermostat switches off at 8 am and hall one takes over again.
3) Some small tweaks, like the hall thermostat has the stops put in giving a maximum of 18°C, because there is also now a thermostat in the kitchen which is programmable, if extra heat is wanted it is easy to lift up the heat on this one, and 5 times a day it auto resets, so does not matter if anyone forgets to turn it down again. Also set target temperature 3°C higher from 6 am to 8 am to ensure valve fully open if required for those 2 hours, after 8 am then it goes to 19°C for rest of day.
4) The big one, removed the batteries on the living room eTRV and refitted, waited for orange LED, pressed button and the head then relined its self with the valve, once the red LED's had stopped flashing the valve went cold.

Yesterday I was out most of the day, so don't know how it faired, today it's quite cold 13°C outside so the living room has not actually over heated, it has shown target 19°C and current 20°C most of the day, the radiator has never really got cold. But walking into the rooms they feel OK which is the most important thing. Not sure the living room eTRV is really working as it should, would like to feel a non regulated radiator in kitchen or wet room and feel them to be hot, and the living room radiator to be cold, then I would be 100% sure it is working A1. So it is wait until next sunny day for that.

It has however been an ongoing problem for some 2 years trying to get the rooms to automaticity regulate to heat required. I hope in the future it will need no manual correction, the house will simply be warm during day and cool at night. Or at least mothers bedroom cool at night.

 

[DP]

Eric, you don't say what the boiler make and model is

Hall radiator should not have a thermostatic valve if room thermostat is located there also.

I would suggest your system needs balancing and possibly boiler needs looked at well

As far as controls are concerned, I would be suggesting Honeywell Evohome here. It will allow you to do everything you desire.

 

[ericmark]

Eric, you don't say what the boiler make and model is

Worcester greenstar 28i junior this was in the heading to thread.

Hall radiator should not have a thermostatic valve if room thermostat is located there also.

Possibly correct, however the idea is the room thermostat is there to stop the boiler from cycling, not to actually control the room temperature, set at 18°C when we have a warm day it will turn off the heating, but the idea is on cold days heating is controlled by the TRV's so each room is independent. The TRV in the hall is about the same setting as the thermostat, because the standard TRV has quite a large range so set at 2¾ it should start turning off around the 17°C and be fully off at 19°C monitoring has shown the room thermostat will activate with the heat from radiator but rather slow which is what I want.

As far as controls are concerned, I would be suggesting Honeywell Evohome here. It will allow you to do everything you desire.

I would agree in hind sight Evohome would have been better than what I have. Hind sight is easy.

The major problem is the control gear does not give information as to exactly what it does, the Honeywell HC60NG instructions do say it controls +/- 1°C and this one actually has a warning system to say if no coms in an hour, the Horsmann HRFS-1 has no warning of coms loss but is +/- 0.5°C this thermostat is used just to give a morning boost it is within a meter of base as it has in the past lost coms and caused both over and under heating, clearly there is a reason why the Honeywell is more expensive, it is more reliable.

But when we move to the plumbing hardware there is very little information, the TRV must have at 2¾ a point when it starts to close, and a point when it's fully closed, I would guess it starts around the 16°C mark and ends around the 21°C it is clearly a large range, the eTRV will be better set at 19°C it will likely start to close around 17.5°C and be fully closed around 20.5°C, but they simply don't tell one what to expect.

I am sat watching TV and at 5:30 pm the target temperature changes to 22°C and I hear the motor opening the valve, at 10:30 pm the target drops to 16°C and again you hear the motor closing the valve, with such a drop the valve should be fully closed, however one hears the motor adjusting the valve three or four times after the valve should have fully closed and well before the room has cooled enough to cause valve to open again.

If one had some idea of what the valve was doing one could work around any failings, but it's all guess work.

From very careful monitoring I have worked out most of what goes on, and now the heating is working reasonably well, I did not expect it would take two hours to raise the room temperature from over night at target 16°C where it actually only drops to current 17°C to target 19°C, because it is so slow the target is now set at 22°C at 6 am then back down to 19°C at 8 am this ensures the valve is fully open in that warm up time, also a thermostat in the kitchen set to 22°C where only heating is towel rail ensures the boiler is running in that 2 hour slot where the house warms up again. Also whole heating turns off at 4 am and back on at 6 am again to ensure boiler is running.

Although I am now getting what I wanted, it begs the question what is the point in having any device which you can alter automatic with the phone? One would need to work 100 miles away from home for an automated system to detect you were on your way home and get the house up to temperature for your return. I see no point at all in a system which needs manual intervention, you don't want to have to set the heating an hour before you leave work, it would be better with a simple timed change, OK I suppose the boss may say don't go home fly to USA straight away, but I think that is highly unlikely, so unless your a wagon driver the phone activated central heating simply would not work.

The house neither cools or heats quickly, the bedroom was set to cool from 19°C to 16°C at 8:30 pm it has not cooled 1°C the living room has faired better from 22°C to 16°C at 10:30 pm it has actually recorded as dropping 2°C on the TRV, but the camera which also records the temperature in the room shows it has just dropped 1°C.

But what is more strange is the living room radiator is stone cold, as it should be, but the bedroom radiator is hot, clearly this will be why the temperature of the room is not falling, target 16°C current 18°C and it's been that way for 5 hours, but radiator still hot. Yesterday it was reversed, it was living room with hot radiator when it should be cold and bedroom was doing as it should with a cold radiator.

 

[DP]

Is it perhaps your idea of how the system should operate is slightly flawed?
Room thermostat, as you correctly said, is there to stop the boiler from cycling
TRVs are there to stop the rooms from overheating
All I am going to say is hall radiator should not have a TRV if room thermostat is installed there.
Radiator balancing point still valid

 

[ericmark]

I have left the system alone for a few days, it seems to have settled down to doing reasonably as expected, I think the eTRV tries to do too much, in hind sight a mistake, but now fitted I will just leave them.