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As far as I can see, the boiler can't fire up on the lowest modulation, and so as the boiler cycles the flame it - very briefly - dumps a lot of energy into the loop. At lower flow temperatures it seems to exceed the set point very, very quickly due to this, hence my thinking the problem will...

Exactly. I'll just make the best of what we have for now, and when the time comes to replace the boiler, I'll get the smallest one we can get away with based on DWH demand. I'd certainly like to add some kind of proper modulating (flow temperature) controls, but as I mentioned a few posts...

The only answer to this is "ask Persimmon Homes" :) . I imagine they just bought a job lot of this boiler to cover every house in the estate, using the largest demand as the benchmark. The model's heating output range is 7.1-25.6kW depending on temperature (and 35kW output for DHW). All for a...

I'm not too confused, but perhaps I worded it badly - my boiler is so oversized that getting OpenTherm controls will make it cycle more often. The minimum output is 7.5kW. I doubt my house would ever lose that amount of heat even at -3ºC, so this means even when the boiler modulates the flame...

I'm struggling to work this out myself. My basic on/off thermostats are doing the job right now - I'm doing a bit of manual "OpenTherm" by keeping the flow temperature artificially low while the temperatures are still mild. But I also know my boiler is vastly oversized and doesn't modulate down...

Embracing OpenTherm is beneficial, but it's not going to slash your bills. Seems to be around 3% savings which means a long payback depending on your initial outlay and usual annual gas usage. As for the other question - it'll start the heating cycle on a higher flow temp, then as you approach...

Most boilers modulate the size of their flame to maintain a flow temperature. If the boiler is set to 65C flow temperature, it'll vary the flame size inside to maintain a steady 65C. This is an innate function to most modern boilers, and you can generally hear it happening based on noise levels...

They argued it on a value perspective. It'll be several hundred pounds to spend for what'll be less than £80 return per year. I myself would be looking at almost £400 to get just OpenTherm on my dual-zone heating, and if it saves 4% at best, that's £38 a year. It's not a great payback period...

Modulation in the sense you first mention is internal to the boiler, so is always there, and so you won't lose it as it's an internal function, so don't worry about that. Think of this as basic cruise control on a car - you set 65mph, and the car modulates the throttle to maintain that set...

Your current Drayton control system doesn't have any OpenTherm capability so your thermostat simply calls for heating on, and your boiler maintains whatever flow temp is set on the controls on the front. Be cautious of terminology here - your boiler is modulating, in that it can reduce its...

The modulation via OpenTherm is a two-way street. You need both ends of the system to talk OpenTherm. Data is sent back and forth - set point, current temp, current flow temp, modulation level etc etc. If your boiler doesn't support OpenTherm (or the thermostat system doesn't support a...

I assume some of the better units that can do OpenTherm can also get the local weather and effectively do both load comp and weather comp together, without needing the local sensor actually attached? I'd say the current local weather should be accurate to within a degree or two of the actual...

Thanks, that makes more sense. So if I went for WC, I'd have to try and guess a happy medium "room temp" on the boiler that would try and negate the delay in reheating. I guess that would be the beauty of an OpenTherm system as it would negate the delay that WC would cause. So it would seem, due...

Sorry, forgot to mention that. Yes, it's hot water from the boiler only. It has the "domestic pre-heat" option but we have that turned off, as it obviously only accounts for a small amount of water. I say airing cupboard as it's where a hot water tank would generally be (cupboard on the upstairs...

Thanks both. Looking at the Ideal manual, it seems that adding in their weather comp sensor turns the flow temperature dial into a room temperature dial, and the boiler attempts to maintain the room temperature based only on the outdoor temperature, not using room stats, needing only an...

Hi all, Looking to get a bit of a sanity check here. I have a new-ish (2017) build house, which is an Ideal Logic Combi C35 boiler, with 2-zone heating (upstairs and downstairs split). The wiring centre and zone valves live in the airing cupboard upstairs, mid-way through the house from the...

Hi Andy, As it happens, I have exactly the same boiler, thermostats, zones (up/down), and even bypassed radiator setups (are we on the same estate?!?). I'd be interested to see how you got around this. I was thinking I could just install the Wiser receiver under the boiler, tapping the boiler...