Heat Pumps - post here.

For Legionella Cycle (typically done at night) and if you want solar powered hot water in the summer you could connect an Eddi (or a DIY relay setup) to turn on the immersion in the unit to divert excess solar.

Am currently in the process of getting quotes for a heat pump install having received my technical assessment report. House is c.180 sq. m coming in at BER B1 with HLI of 1.63. Though initial prices vary as expected I have been quoted HP sizes ranging from 8kWh to 14kWh. My own research suggests I would need something between a 7 and 10kWh unit. Whilst price is clearly important, I'm more interested in having a correctly sized unit, correctly installed. I also have existing solar water heating which some of the installers seem to be balking at. If anyone here wishes to share details of recommended supplier/installer, can you PM me the contact info? I am in North Leinster.

I will also post more details on the thread as I get additional quotes.

Tks.

Hi, I am having issues with Daikin Altherma heat pump, it remains powered on but the flow to the radiators is intermittent i.e. on for approx 5 mins off for approx 5 mins (times never consistent). Looking at temps etc in the sensors screen there doesnt seem to be any obvious trigger for what is making the flow rate drop to zero and then kick back in again.

Any thoughts?

Has anyone used a retrofit underfloor heating system like below

Is it something that could be done by a DIYer, assuming they had a decen plan to work off of?

Ok, so I spoke to a few installers today and here's what I learnt in relation to using solar pv with a heat pump...

1. In winter time, your heat pump will probably be on most of the time at a low level... so considering that there isn't much sunshine, all or most of the generated electricity will be used by the heat pump. If its not, its sold back to the grid. All good.
2. In Summer time (plus late Spring / early Autumn) you may not need heating in your house (considering it'll be very well insulated). You will almost certainly have excess solar PV electricity. So you can use that excess to heat the water in your cylinder with a diverter plus immersion.
3. Yes, you could use that electricity to heat your hot water with your heat pump instead... BUT the issue here is that you don't know when the sun is going to shine or for how long. Heat pumps don't like this.... they are most efficient when they are on for a prolonged period of time at a low level. It's definitely possible in theory, but complex. (I'd imagine you'd want to have some sort of program that would use weather forecasting information with hot water demand analysis to best figure out when to turn the heat pump on and for how long.)
4. Anyway, the point was that just using a diverter is much easier... because it can heat the water whenever the sun shines, and whatevs, its going to be excess energy anyway which is cheap.
5. I was told to investigate ugly "pre plumbed cylinders" rather that the flashy "all in one boxes". Apparently the flashy boxes are designed for countries where people tend to put them in their kitchens, whereas in Ireland we tend to put them behind doors anyway... so there's no need for them to look good. Preplumbed cylinders are much cheaper apparently.
6. I was also told to make sure that whatever system I choose can use a diverter. I think Joule require a second immersion coil, which is possible but you have to request it.
7. Samsung and Daikin make good heat pumps
8. Joule make good preplumbed cylinders

I like the idea of turning the heat pump off for the Summer. You'd imagine that would extend its life.

That's just what I was told! Interested any further thoughts / opinions / perspectives.

Thanks, none of the zone valves close and it does it regardless of setpoint. I will keep digging.

https://www.thisismoney.co.uk/money/bills/article-11830589/How-heat-pumps-leave-homes-cold-owners-having-ripped-out.html

I don't think anyone is arguing against that. The issue is that the airtightness/insulation level required to run one efficiently is fairly high the reality is that there are loads of horror stories out there. And you'd question any program that aims to push the installation of heat pumps that doesn't require the house to be at the required level to run it efficiently. Our BER rating is useless in this regard, an A rating doesn't mean the house is suitable for a heatpump.

HP and A rating were never in lockstep, the HLI is the key number, but of course referring to that wouldn't help with pi**ing in on the BER

My take on this notion of using excess PV to heat water is fine, IFF you have use for the hot water on a daily basis.

You might heat 110 litres but does it get used?

We are fixated with our hot water cylinder, without any regard for the heat losses associated with it.

Eg, if I run my kitchen hot tap once a day for a year, from an immersion heated by electricity, that wastes 60 kWh of electricity, enough to drive 320 kms in my 2017 Leaf.

Likewise, if I use my externally located oil boiler in summer to heat the hot water only, the heat losses are astounding with the long pipe runs and maybe 40 litres in the boiler itself, not to mind that part of the 100 litres that is not used.

Hot water heated at the point of use is the way we are headed: etc showers, under sink heaters, electric kettles, hot water taps etc etc.

Storing excess PV as electricity is much better idea as its a much higher form of energy and much more versatile that a cylinder of HW.

There are minimum fabric U value requirements when above 2 and less than 2.3 but 2.1 is not too insane.

mb will be too small for HP.

GP needs to go

When replacing rads, use a delta T of 30 rather than a delta T of 50 when looking in the rad books.

The easy way is if you have a 1.8 by .6 SP rad, , look at the het output in the delta T of 50 page and then look for the same output in the delta T of 30 page, this will give an idea of the new size required

Can’t agree more and why I cancelled our Eddi and replacement HWT as part of our solar install. We’ll remain on the electric shower. It’s more efficient on electricity to heat the water at source and on-demand, as you say.

Cost efficiency is another matter. Heating a HWT to feed the rest of the house only works when night rate electricity is cheaper to heat. Or with a heatpump due to the COP. So the cost of the heat losses are less than the cost saving. Or if you’re being charged peak rate electricity to have an electric shower when that could come from a HWT heated on cheap night rate.

Ok, if people are on deemed FIT export it makes sense for them to dump into the HWT. As they are getting a credit whether they export or not. That deemed FIT export won’t last forever. That's a loophole really.

And even to get hot water to our kitchen tap, we need to run the tap for agessssss to flush the cold water in god knows how many meters of pipe from the HWT. That’s a waste of water too (water efficiency drops). If we paid for water usage, I wouldn't do that. Some devices only have a cold feed now (washing machine or dishwashers). They won’t let you plumb in hot water. 

We don't heat water outside winter. HWT remains cold water for ~7 months of the year. I boil water to shave - not a huge ordeal.

I'm not sure it would, possibly the opposite!

Well I don't think there's going to be a ban on gas or oil boilers. What is more likely is that building standards will be updated to make gas boilers no longer an option for new builds or retrofit

This is pretty much the case already but the government may go a step further by imposing carbon taxes on house sales below a certain BER to suddenly make retrofit a financial imperative

I do think that retrofitting is never really going to work and the only way forward in Dublin is mass purchase, demolition and replacement programs. Take the old low density houses around the city centre and replace with higher density, higj quality family apartments

Then again I'm one of these crazy people who thinks planning and design should be centralised, that Dublin City council should acquire land, contract out the construction of homes and then sell some for profit and use others for social housing, and that city centres should be primarily designed around pedestrians and bikes

Apparently this makes me one of "them" according to the conspiracy theorists 😁

Ours is 1.87. Along with the ATT result of 4.51, is this a bad score?

New build A2 with mechanical ventilation.