Heat Pumps - post here.

Ya its pretty high. Yes, have had more than one look at the setup. Days with frost all day I can hit 100kw (heating and general elec). Hot water is around 7-8kw. I suspect the buffer tank could be removed. A new system would not have two circs at manifolds, 7kw straight way saved by not having them running most of the time.

the big Q is how many KW would a new pump use - extremely hard to quantify it. There are is no remaining paperwork for UFH to assure ourselves everything is sufficient.

Please challenge me on the following calculations!

Heat geeks suggest a 2006/7 house has heat loss of 40watts/ SQM. And suggests multiply this by 1500 to get annual heat loss.

40watt*350metres*1500= 21,000,000 watts, or 21000KW of heat required per annum.

assuming COP of 2.5= 8400KW of actual electricity input required

If my heating is required about 150 days a year, this suggests 56kw per day.

If my current average is 50-60KW, this suggests I am more or less in line with HeatGeek rule of thumb? It seems hard to believe, but this is what has left me unsure that a new pump will result in drastically reduced usage!

For some comparison, if this logic is correct those in a 250sqm house would need 40KW a day with a 2.5 COP, and 33KW per day with 3.0 COP. A 2009 or better house could be half that (being closer to 20watts/sqm).

rooms generally 19-20 upstairs and down. Do you mean 2.5kw using a heat pump? Mine is ~7-8 using immersion, Our tank is huge. Family of 4, two rug rats frequently using bath.

Were you not saying a few posts back that you use 22kwh per day in summer which is hot water only? This is using the heat pump?

But you’re also saying that you can get a days worth of hot water using 8kwh with an immersion?

Can you explain?

"A COP of 2.5 is low even Heat Geeks claim that 3.5 COP should be the min if setup correctly."

a recent UCD study and oireahtas report suggested over 50% of heat pumps and other eco-tech in ireland are not being installed properly! This is heat geeks main value prop - they are vehement that most systems are being installed poorly.

If they did a study around insulation retrofits the outcomes would likely be similar unfortunately. My estate is littered with poorly installed external insulation, its sad as people are paying a lot of money and the contractors are likely pocketing the grant on top.

It certainly appears to be one device that can physically be installed perfectly, but can be royally fooked up with incorrect settings

My personal opinion is that heatpumps, while will physically be installed by plumbers, should be designed, spec'd and commissioned by heating engineers.

The big problem I see especially with plumbers is that they do things in ways that "they always go it", which doesn't mean that it's the right way. And this starts with balancing rads, using guestimation rather than tools like an IR Camera or at least thermometers.

I have little doubt half the insulation and pumps are being flung in incorrectly, all you have to do is looking at the amount of forum and facebook threads about heat pumps costing a fortune, more than oil....my own pump is a disaster, but mechanically it seems to be working as prescribed, the issue is most likely in the location, size, and decisions around buffer tanks, hot water tanks, circulation pumps, UFH pipe lenghts etc.

25 for heating /dhw or total for house? How big is your house?

Still good usage. I'm similar in below freezing for heatpump. Currently 15- 18 in these conditions.242sqm

Yeah a2 in Midlands myself. Below 20 is chilly to be watching tv in. 21-22 herself has to have ha.Some days last winter total house usage 70kwh.Wednesday was 22kwh for whole house. Alot people just think it's normal and never alter an y settings.

Should be setting in installer. I changed to fixed in October a d hhad do that in installer mode. Much happier. Took week or more to find lowest flow temperature keeps house warm in any temp. 29 or 30 does the trick for my house. Cycles too much 28 and below.

Just a note on your 40% reduction in units; new builds typically are drying out for the first winter (or two depending) and this drying process costs energy so some of the reduction seen may be because of this.

What brand is it? I have an IVT/Bosch it only allows you to change one end point as well.

I dont think weather compensation is an issue, you just need to find what the suitable flow temperature is for your specific house. Lowering the heat curve will lower the flow temperature. Once you get it right, the temp inside should stay fairly consistent no matter what the weather is outside. The methodology i followed is here:

• Adjust the heat curve to a suitable flow temperature (say 31 for underfloor), at expected minimum outside temp (I used -6). I read that for every degree you can lower the curve, you save roughly 3% on energy consumption.
• On the heat pump set the desired room temperature (I used 21 as this is default heat curve, without an parallel offset). This isnt a measured temperature, but is used to parallel offset the curve.
• When it is around 0 degrees or preferably less outside, check if the desired room termperature is achieved in a suitable reference room using a termometer. If it is 2 degress too hot inside, you can lower the curve. Opposite if too cold. Wait 24 hours before more changes are made.
• Once you dont need to adjust anymore you are at a suitable temperature.

All thermostats must be set to maximum in the house and any indoor sensors must be disconnected when setting the heating curve.

Just to note as well, almost all my room stats are not accurate anymore, some are more than 1 degree out when checked against other new termometers. They are only 6 years old and I didnt use them for this exercise.

It is described here for geothermal pumps, but is the same prinicple. You will need to translate. The Key part is about half way down the first post. https://www.varmepumpsforum.com/vpforum/index.php?topic=48516.0