owh2021

The thermostats are linked to a Heatmiser control panel which controls the actuators and manifold pump, and also sends call for heat direct to the FTC6 controller.

Thanks Temp, really helpful. Looks like I had totally misunderstood how a 2-port buffer works. I think that looks like the best solution if we have the space for it. Time to see whether the installers agree if a buffer should have been designed in.

I think that pump is already at its max - currently speed 3/3 proportional pressure curve. I'll have a go playing around with some zones always open as you say. Bathrooms and bedrooms are on one manifold and the living rooms on another. What seems to happen is the living areas reach temp long before one of the bathrooms does, so the actuators close, leaving only the bathroom running and the cycling begins. The master controller is just setting the flow temp. The rooms temps are by individual Heatmiser stats in each room.

Many thanks both. Stones, I think I understand what you are saying re. running as a single zone. The problem with that for the way we live is that we tend to have the bedrooms quite cold and the bathrooms/living rooms warm. That makes running the first floor as a single zone particularly difficult. I could also see some difficulty balancing things whereby we would have some rooms overheating whilst the bathroom is still trying to play catch up - as I'm convinced there isn't enough ufh pipework in there. How exactly would it work installing a buffer? As simple as 2 ports - return-in and return-out on the primary return? That would solve the volume issue but would it do anything to improve flow rate with only one or two small circuits calling for heat. Presumably given enough time with low demand, the buffer temp would also match the flow temp, then the unit goes back into cycle mode, and the UFH loops can't benefit from all the hot water in the buffer because for some reason the heating pump also turns off with the cycling. OR perhaps the pump will continue to run, supplying heat to the ufh because there will no longer be such a flow restriction... Clearly I'm confusing myself, but I can at least approach the installer now and see what they suggest.

Thanks. There is definitely no buffer tank. The DH all runs without fault. I'm a bit confused between buffer tanks with 2 ports, seemingly acting as a volumiser, or 4 ports where presumably a stat is fitted to the tank which controls the call for heat. I assume I need one of the above. Any idea how buffer tanks are sized? We have quite a limited space to work with since everything is fitted in a cupboard off a wardrobe area.

Hi all, We are having some problems with a new Ecodan install and with the heating now on it's clear that it's not performing as expected. I want to check I'm on the right tracks before going to the installer and getting another TADTS type response. 8.5kw Ecodan serving two UFH manifolds: GF - set in flow screed approx 70sqm, 4 zones FF - grooved overlay panels (12mm pipe), 70sqm, 3 zones. When there is a call for heat everything fires up as expected. However if only a couple of zones are calling for heat it will run for just a few minutes before switching off. Not just the compressor cycling on/off but also the heating pump (I would have thought with short cycling that the pump would continue to run and just cycle the compressor on/off depending on return temps?). It then sits dormant for a good 15 minutes before repeating. It often won't run long enough for the UFH return loop to even become warm. I can see from the thermistor readings that the return temp matches the flow within a few minutes. I expect the problem is exacerbated by the small-ish 12mm pipes on the first floor as the flow through these must be tiny compared to the flow from the heat pump. I think we might have a minimum volume problem and/or a flow rate problem. Can anyone confirm if that sounds right and what the correct solution would be? Many thanks, Olly