Michael_S

We have two cheap 12l rated dehumidifiers, both can be run off a smart plug as restart with power restored. We are running home made fancoil with 80mm PC fans, but even with 8 on a rad it does not make too much difference, we combine with ceiling fans to move the cold air again but still only cooling a couple of C (27-29 inside cf 35-37 outside) - record dew points of up to 24C have meant we have had to increase flow temp to avoid condensation which hasn't helped. Dehumidifiers have been extremely productive with the high humidity of the last week. My understanding is the latent heat of condensation only adds a little to the effective heat released so more like 125% of the input electricity is converted to heat not the 300%+ plus of a heat pump.

Did you see what the dew point was at your location? We have been running at 16C with one artificial 'fan coil' and only had condensation on the rad in the bathroom after showers, others are bone dry, not a sign of any dampness let alone dripping, despite the dew point sometimes spiking up to 19 and averaging about 16. What is harder to work out is if we are getting any significant cooling, we are getting major cycling and only using about 0.5kw so perhaps up to about 2-3kw of cooling but no whether that would give an appreciable cooling effect?

Yeah - it definitely doesn't run backwards or have the heat/cold kwh registers that some models have so agree it can give instantaneous output and possibly if I understood modbus or whatever could give telemetry but I don't and suspect it would need extra modules to do so?

Not a lot of software on our heat meter, it is a Danfoss Sonometer 1100, it has a screen you cycle through that gives you live readings for flow and return temp and volume and a calculated heat transferred in kwh measured since the unit was new, nothing else.

The heat meter measures the flow rate and flow and return temps and calculates a kwh heat transferred number which normally just increases like an electricity meter. Not sure if the return is warmer than the flow if it will decreases the total kwh transferred counter.

Not sure if we can calculate an EER, we have a heat meter but not sure if it counts backwards..... Gonna add some more fans to the rads and overvolt them a bit to see if we can get some more airflow - I know you can get actual sit on rad units but the fans are less than a quid each compared to about £100 for a unit that will only do about 1/3 the length of a fad and is probably louder too. Currently we are using our second hand heath robinson heat pump - hoping to move to a 'proper' set up but MCS sound rules mean our preferred placement is max 55db that seems to strictly limit the number of 8-10kw units available and the one that seems to be best fit (Grant) does not cool. Does anyone know of any other units that fit the 8-10kw and 55db or less sound power criteria and do cooling? Thanks

All the rads are ok except the bathroom that is sweating a little, I guess we could just turn that one off?

WE are running our flow at 16 (checking dew point to avoid condensation) and have some cooling. We have mounted 8 PC fans under one rad as a proof of concept and it helps creating a small local cool zone, they are silent but we could actually do with considerably more airflow, may try a higher voltage power supply. Currently they are fixed using mini magnets but not that secure so may try mounting them using plastic trim strips. Heat pump is drawing about 1/3 minimum input on an hourly basis and cycling frequently showing we are basically failing to extract nearly as much heat via the rads as the unit is capable of even at minimum modulation. Inside air temp is 26C compared to 35C outside but no idea what it would be without the cooling.

So I have upped the breaker a bit and it isn't tripping currently but that is obviously only a short term solution. Given the nature of compressors, fans etc what sort of level of leakage current is acceptable? AI suggested I try and watch to see if the break happens for example as the fan tries to start or as the compressor starts.

Any suggestions Our LG Therma V 12kw U32, about 10 years old works fine.... ...except when it gets warm and sunny when the unit suddenly decides it will trip the fuse with leakage overcurrent, it does this even if working at low power, heating or cooling. Any ideas why we might be getting leakage current only when the unit is exposed to hot sunshine? Thanks

To be fair, last week with the easterly flow DPs were very low across the board despite the solar warmth. I have just bought a bunch of computer case fans and and going to see how they work with our double rads and flow temp controlled to be above dew point; we will probably run the dehumidifiers in the summer when we have excess PV so minimal cost which should also help with this issue - at the expense of some additonal heat input from the dehumidifiers.

Just wondering how heat pump quotes are calculated. For example my quote of 6200+7500 for a zero disrupt install (no cylinder, no rads) with a heat pump costing 3.5k, a 10m cable run and a 3m pipe run just seems crazy unless I am missing something?

I would like an effective zero disruption install. I think I could use a 9kw Grant Heat Pump costing 3.3k inc VAT run the cabling and pipework myself and even position the unit (total cost about 5k?) so it would just need someone to connect the electricals at the meter end, sign off on everything, inform the DNO, confirm it meets the BUS requirements and whatever else in order to get the BUS grant. Even without this would seem cheaper than the 6k after BUS that I have been quoted. Thoughts?

Space is fine, existing cylinder is properly supported with a steel, but was installed during an extension and the loft hatch is too small for a 600 diameter cylinder to pass. I never understand how the quotes are so much - this one is 6200 after the 7.5k has been taken off for basically install unit on side of house, run about 3m of pipe and tee into existing heating/hot water circuit with a diverter valve needed.

Yeh - strange on the cylinder, with 5 beds I thought MCS would insist on bigger but the optional cylinder upgrades are only 175l or 210l ?? There is no specific mention of whether they would be using a plate heat exchanger rather than the existing coil. Our loft hatch won't fit a standard cylinder so keeping the current one has advantages.....