My DIY installed Vaillant AroTherm Plus is now LIVE

THE ALM

https://www.boards.ie/discussion/comment/122699056#Comment_122699056

They mean in terms of their weather curve and being 40° at 0°, sorry I wasn't clear on that.

It does run on weather curve based on outside sensor just on a lower curve compared to their recommendation for rads.

championc

The meter is GONE !!!

John.G

How does the inside unit, the condenser, "work", where the compressor gives up its heat from a coil in a cylinder, a sort of buffer tank where all the water in it is circulated through the rads or UFH and through the HW cylinder heating coil, what are the flow/return temperatures?, what capacity is this cylinder or buffer tank?.

Is the compressor variable speed?

championc

I have NO buffer tank. The house is all rads. There is no point in heating volumes of water which are not necessary. The heat pump unit has an internal reservoir of a litre or two (the heat exchanger), which is what is heated before being circulated around the rads circuit.

Flow temperatures are dictated by a weather curve setting, which are relative to the outside temperature.

Current flow for our house is mid 30's, but flow is, at the end of the day, whatever is needed to replace the heat being lost.

John.G

What is a typical flow/return dT

Is the ASHP variable speed?

graememk

Just want to add, with monoboc there is no inside unit at all.

I have a ecoforest myself but has very similar design, compressor is inverter driven so is variable. The internal storage in it is just the heat exchanger.

To heat domestic hot water, you just have a 3 way valve that switches from radiators to hot water and also a different temperature profile for that.

championc

https://www.boards.ie/discussion/comment/122819052#Comment_122819052

dT should ideally be around 5 Deg. Fast flow is facilitated by having the right pipe sizing. For instance, you cannot have a 1/2" feed pipe branching out into 4 x 1/2" connected rads. The AroTherm 5kW unit pump runs at 860 l/hr

John.G

Does your unit display the evaporator and condenser pressures and temperatures?

What refrigerant are you using?

zoom_cool

Good night tonight to test @championc

championc

https://www.boards.ie/discussion/comment/122829015#Comment_122829015

It is indeed

Ours is running constantly since about 14:00, hovering around 800w constantly.

But the house feels lovely - the best ever. No feeling of cold spots, but not toasty warm either.

Seems like the compressor is running around 50% of the max speed I have seen (40 RPS).

According to my stats on Econcms (link in the first post), I have a COP of 4.24, electric usage of 9.5kWh and generated heat of 40.3. it will run for another hour. I only run it from 10:00 till 23:00 daily.

If we were still on gas, we wouldn't have the same level of heat throughout the house. We previously only really heated the rooms we used. We would have needed to burn about 6m³ of gas for 60kWh of gas for about 40kWh of heat.

serox_21

How was the heat pump behaving last 2 days considering lower temperature and high outside humidity 94-95%.
Were there many defrost cycles.
I noticed a few small gaps like on/off on your graphs for last 2 days between 12PM-2PM. Are those defrost cycles followed by 1-2 hours of running almost full load(2kw input, 7 kw output power).
What is the max flow temperature set for heating the house. Noticed around 42-43 C for outside temp of 5-10C.

Is it set to reach a temp of 50 or more for lower outside temps?
Looks like it takes a few good hours to reach the 20C temp target temp in the house after being turned off for the night.
It will take up to 4PM(6 hours) to increase the temp from 18C to 20C.
Are you planning to let it run over the night as well?
Maybe for a few days to see how the COP is with a full 24h runtime. Last night 12/13Nov inside temp was low, 16C. Not a comfortable temp for most people.

DC999

https://www.boards.ie/discussion/comment/122829080#Comment_122829080

Beyond jealous! We've 2 small electric rads running at a combined 800w. You're heating your house for our 2 rooms! Hats off for the self install

John.G

To satisfy a room temperature of 20C with a OAT of 5C my rads need to run at 60% output (of their T50 rating) with flow/return temps of ~ 56C/51C. If I ran with a flowtemp of 42C then I would only get 29.4% output so to get a decent COP at 42C would need to upsize the rads by a factor of 2.04.

At a OAT of 0C my rads need to run at 80% output with flow/return temps of ~ 65C/60C so would require a upsizing by a factor of 2.7 to run with flow/return temps of 42C/37C.

I would certainly be looking to upsize the rads by a factor of 2.0 if I ever install a ASHP.

championc

https://www.boards.ie/discussion/comment/122833822#Comment_122833822

There is a max temp setting, but this is a threshold and has no bearing on the flow temperature whatsoever. Flow temperature is totally dictated to by the outdoor temperature sensor. It does in some way work with the indoor temperature if you want.

The gaps between 12 and 2 are purely cycling. I run the house at 19 deg up to 14:00. So the minimum heat delivered is greater than the heat being used.

I have had no defrost cycles yet.

I have no intention of ever running the house 24hrs. We never did before and I don't see why I would suddenly start doing it now. I am downstairs each morning for 20 mins before shooting out the door, so I'm not going to heat the house for that - and never did previously.

The main thing for me was the setting of the weather curve. Set too high and the water heats too hot and leads to more cycling. Loo low and the house won't heat - simple.

I have it set to 0.60. Yes, whether it was 5 deg or 10 deg outside, the rooms still heated up to 21 (the sensoComfort unit reading is a bit out). Yes, from 14:00 it only got up to temp by 19:00 or later, but that was perfect. When rushing around, you don't need the heat as much. That's why from the morning until 14:00 the max is 19 deg. The missus doesn't want it hotter. You also get some solar gain too invariably

championc

https://www.boards.ie/discussion/comment/122834589#Comment_122834589

What you should do is to start and experiment by turning down your boiler temperature. It may surprise you how well the house heats, but of course it won't get up to temperature nearly as quickly.

The one thing that has surprised me is the air changes per hour. They aren't nearly as high as I designed for. Mind you, I never planned to heat the entire house as we never did before, but we now do as it's cost per m² is definitely lower and it reduces the chance of cycling in the mornings

John.G

https://www.boards.ie/discussion/comment/122836007#Comment_122836007

Yes, and because a lot of the winter time is spent between 5C and 10C then I could just boost up the rads in the morning for a hour or so and then reduce the flowtemps again as my heating is on for 16 hours/day. With my existing rads this is the sort of settings I require, if I do install a ASHP I would just install a extra rad in each of 4 downstairs rooms as we only maintain the upstairs at 17C/18C.

Radtemp OAT Radoutput

75C -5C 100%

65C 0C 80%

55C 5C 60%

45C 10C 40%

35C 15C 20%

DC999

https://www.boards.ie/discussion/comment/122836007#Comment_122836007

Did you do anything to reduce air changes pre heatpump?

championc

No. And I saw a YouTube video of Glyn Hudson who said the same thing.

So the best measure is really using your gas boiler as a sort of test / benchmark

Take a daily meter reading of the gas meter for a week. You'll have a rough idea of your boilers' efficiency. So then you have your daily heat requirement - or at least an indication

championc

Some people looking at my data will have seen intermittent heat generation stats from midnight to 9am. This is the pump running to ensure that the water in the system does not freeze with low overnight air temperatures.

The MOST IMPORTANT thing with getting a heat pump installed is getting Live Data. Data is King. Apps are a guide, but you won't see stuff like the pump running but no power (except a few watts) being used

10-10-20

@championc, did you say somewhere that you installed a heat-meter on the new A2W system (or am I dreaming) or did you just integrate it with Econcms with a Raspberry Pi?

championc

All data on emoncms is extracted straight from the unit over the eBus using an https://ebusd.de

championc

Yes, the flow temp is up as expected and the unit is working hard.

Main thing is that the house is lovely. It honestly is the best temperature ever - nice and even, rather than heat blasting out of one wall

zoom_cool

Hi Championc I hope you don't mind me giving you advice I think you are running flow too high it is more efficient low for longer.

I run my heat pump at 33 at 0 with 0.5 slope and keep house at 21 degrees every where I do have UFH downstairs admittedly put have Rads upstairs it's a 200m2 house old but renovated.

What is your weather curve at? I have attached my settings. I have a Phinx R290 8kw heat pump the below consumption includes DHW in a 300 litre cylinder.

championc

No problem @zoom_cool .

We have a sh1te 70's 3-bed semi made of cavity blocks. So it's winning no prizes for insulation, nor has it a hope in hell of running at 33 Deg flow. With usage of about 22kWh yesterday, that for me is a complete success.

I'm running at WC of 0.6, and it seems bang on. It is just about able to maintain 21 Deg. Yesterday too confirmed that a 5kW unit was indeed the right size

But it clearly shows how many variables are at play with heat pumps, and one size doesn't fit all. But a wrong setting or two, and my power consumption could easily have doubled

zoom_cool

Fair enough I have a 1950s house but did external wall insulation which helps a lot. The problem is you know what you are doing a lot of plumbers won't set them up correctly for the general public. I am like you I will tweak and read it to understand but vast majority won't if you look at the Facebook groups it is full of negative installs

championc

I'm just an enthusiastic DIYer. I knew nothing before I started researching. But I knew if it was to work, it needed to be gone right and get the right settings.

I was determined NOT to have a buffer. It has done defrost cycles, so I know that there is enough volume in the rads for it.

IMO, while plumbers can do physical installs, in reality, heating engineers should commission them

championc

https://www.boards.ie/discussion/comment/122867516#Comment_122867516

External wrap is next summers Project. Fully approved clearance by ATC !!!

10-10-20

https://www.boards.ie/discussion/comment/122868324#Comment_122868324

Are you brave enough to DIY that too? 😝

championc

https://www.boards.ie/discussion/comment/122868684#Comment_122868684

Bl00dy sure. It would cost about €20k net. There is no way that it would save anything like this cost in my lifetime. Might get someone to do the final rendering though.

championc

Update : Exceeding expectations in this cold weather. COP of over 3. Using about 20kWh per day.

Super delighted - overall SCOP currently 4.0