Ecodan 6kw Help

[Jordan]

I have just had a 6kw Ecodan installed (retrofit)

 

I only have radiators and no ufh, I am looking for some guidance on optimisation as the installers didn’t really delve into that and cannot seem to find much info online.

 

I have read a little on altering the heat curve but yet again can’t find any guidance on what levels would be best.

 

any advice and guidance from other expertise/ experiences

 

thanks

 

 

 

 

[IanR]

I can't give specific Ecodan advice, hopefully someone will be along that can help with that.

 

But a couple of general questions. How was a 6kW ASHP chosen? That's a relatively low output, so would typically be in a well insulated (above Building Regs) and air tight home. Does that describe your home?

 

Have you increased the rad sizes as part of retro fitting the ASHP? Has any one done any calcs to suggest your flow temp to the rads?

 

Heat curves are to finesse the performance of the ASHP as the temperature drops. We're not really in the heating season yet for a well insulated home, so if you are experiencing space heating issues, it's unlikely they will be fixed by changing the heat curves, it's more likely to be a general flow/return temp change that is required.

[ProDave]

I havent bothered with a heat curve, I just run at a constant flow temperature.  If you do that, it is just a case of finding how hot is has to be on the very coldest day to provide enough heat.  Only once I know that would I then consider implementing a heat curve to reduce the temperature when it is less cold.  to try a heat curve without knowing even one data point would be just too many unknowns.

[Jordan]

IanR-6kw is what was suggested by installers, but to answer your question no it isn’t insulated very well( I am hoping to have cavity wall and improved loft insulation soon) and definitely not air tight.  Yes all the rads have been upgraded slightly in size and from singles to doubles. When you say constant flow temperature do you just mean setting a temp on the thermostat and just leaving it? 
 

nobody has suggested a flow temp to the rads it was just setup to manufacture settings and they gave my wife basic info and then left( I am currently in dispute with the company I’ve the whole process they have been terrible)

 

 

ProDave- thanks for the reply I am really at a loss with all this I feel I have rushed into this and not done enough research and to go with that had bad installers hence me been here and trying to make the best of a bad situation

 

thanks again to you both for your reply 

[IanR]

Flow temp is the temp the ASHP heats the water to that is sent to the rads. And Return temp is the temp of the water returning to the ASHP from the rads.

 

The lower the flow temp, the more efficiently the ASHP runs, but you need larger rads or UFH to get the flow temp down.

 

Until you know otherwise, I'd leave the heat curve at default, and get the rads warming up. They won't be as hot as your previous gas/oil/LPG boiler could get them, but they shouldn't need to be if they've been enlarged.

 

Have you found a setting for the space heating flow (or return) temp on the ASHP controller?

 

This will be different to the flow/return temp for the hot water.

 

P.S. unless your floor area is on the smaller size, I fear your ASHP is undersized, until your insulation is upgraded.

 

The installer should have done heat loss calcs to determine the ASHP size.

Edited October 18, 2021 by IanR

[ProDave]

What I am trying to say is the heat curve thing is a means of getting the very best eficciency from an ASHP by reducing the water temperature when it is not very cold.  But to set it up you have to have some knowledge of how the system performs.

 

So start with the heat curve disabled so the ASHP just produces a constant temperature of water.  Your first goal is wait until the depths of winter when you can turn that water temperature up and down, and by experiment find out just how hot it has to be to get sufficient heat into the house on the very coldest days.

 

Only when you know that, can you turn on the heat curve function and set it to  progressively lower the temperature when the weather is less cold.

 

I am not familliar with the Ecodan, so hopefully someone can give you some help to understand how to adjust parameters and what they mean.

[Jordan]

I haven’t found this from the paperwork the installers sent be I assuming this is the heat loss calculations they have done however I have no idea how to make sense can anyone help to see if a 6kw ashp is sufficient 

[IanR]

27 minutes ago, Jordan said:

I haven’t found this from the paperwork the installers sent be I assuming this is the heat loss calculations they have done however I have no idea how to make sense can anyone help to see if a 6kw ashp is sufficient 

 

18°C Design Temp seems a little low to me, did you give them this as your target internal temp? It would be good to know what outside temp this was done for.

 

Are you very air tight? The Air changes per hour ranging 1.0 - 3.0 is low for a "normal" house.

 

The 5021.29 kW figure is the Total energy loss (assuming all rooms are shown on the sheet), at whatever outside temps they've allowed for. So you need 5kW of energy from your heating system to maintain the Design Temp.

 

A 6kW ASHP doesn't provide much headroom for hot water production, nor raising the temp if you've let the temp drop. If they've used a very low outside temp, say -10°C, then maybe this would cover the lack of headroom.

 

But, with the low design temp, low AC/h, and lack of headroom, at first sight the heat pump looks a little undersized.

 

Edited to add:

 

Do you historic data for how much Gas/Oil/LPG you used to use annually?

 

Edited October 20, 2021 by IanR

[Jordan]

Thanks again for your reply we didn’t specify a preferred room temp this is just what they have done on there on own back.

 

we are certainly are not very air tight built in the 1960’s 10 years plus double glazing and no cavity wall and poor loft insulation.

 

this document shows some other data that may be helpful 

 

thanks again 

EPE - Nuttall NG4.pdf

[Jordan]

I think I was told all the calculations are done at -3 

[Jordan]

A thing also to add here is that the EPC was completed incorrectly sighting that we have good cavity wall and loft insulation, will this affect the calculations also?

[IanR]

It doesn't sound good. They should have used around 10 AC/h for your air tightness, and -3° is not low enough for worst case energy loss calcs.

 

I'd ask them to take you through their calcs.

 

Maybe they'll have an explanation.

[Jordan]

Ok I will speak with them tomorrow thank you for your advice, does the EPC affect these calculations?

[Jordan]

Is there anyway I can prove that they should have used a higher ac/h?

[PeterW]

EPC and no cavity wall or attic insulation means you should not have qualified for RHI. Essentially this is borderline fraudulent and if they did the EPC then they know this. 

[IanR]

47 minutes ago, Jordan said:

Ok I will speak with them tomorrow thank you for your advice, does the EPC affect these calculations?

 

The EPC also also states your properties heat/energy loss calcs, but they are done in a different piece of software, so should directly effect these calcs.

 

46 minutes ago, Jordan said:

Is there anyway I can prove that they should have used a higher ac/h?

 

Air tightness is measured at a 50Pa pressure difference, between inside and outside the house. This way of measuring is common across Building Regs, EPC, SAP calcs. They don't state their AC/h  figures are @ 50Pa, but I'd assume that they are. I guess their software could calculate energy losses with air tightness at a lower pressure difference, but it's unlikely.

 

Building Regs, EPC and SAP calcs actually use a different unit to AC/h (Air Changes per hour).    m³/m².h @ 50Pa is typically used. AC/h is measuring how many times an hour the entire volume of air is exchanged in the property, and the other is measuring how many cubic meters of air, for every square meter of the thermal envelope (ground floor, external walls, top floor ceiling) are exchanged every hour.

 

By coincidence AC/h figures are generally quite similar to m³/m².h figures, for normally proportioned houses. Maybe 1 AC/h = 1.25 m³/m².h in average terms (although this will vary from house to house).

 

Max Air Infiltration to meet Building Regs for a new build is 10m³/m².h, A well built (mass produced) new build will be around 5m³/m².h

Older properties will be much, much worse.

If you drop below 3m³/m².h, building regs expects you to have whole house mechanical ventilation, to ensure enough fresh air is entering the house

 

Putting 1 AC/h, the equivalent to 1.25 or 1.5 m³/m².h for your property is under-estimating the energy losses due air infiltration, I believe.

Edited October 20, 2021 by IanR

[Ferdinand]

Can you tell us  a bit about your property - suspended or slab floors downstairs, rating of your 2G, how much loft insulation etc.

 

You  may, for example, be able to get free 250mm loft insulation if it is a normal loft. Are you in receipt of any benefit making you eligible for the ECO3 programme?

 

The bills going up (as per attachment) is not the normal aim ?, but at least if you are in a position to upgrade the fabric of your house then you can reduce your required demand which may get them back down again.

Were any changes made to your radiators? eg larger sizes etc.

 

Here is a piece I wrote about the usual easy things to do to reduce your bills in a traditional house. Now is not the time to switch.

 

Here is the Govt energy advice website. Basic but there are a lot of sharks out there with websites trying to look official.

https://www.simpleenergyadvice.org.uk/

Ferdinand