Grant ASHP DIY install

[ProDave]

That looks just like the one I wired about this time last year and posted the picture of some of the plumbing above.

 

 

[Bonner]

Condensate is clean water and small volume, should be able to go anywhere. I have a small soakaway under the concrete pad.

[sharpener]

And not acid like boiler condensate so no need for limestone chippings in the soakaway.

 

Probably better doing this than putting it into a foul drain, you might get smells and I can't think of a good trap that doesn't dry up in summer or have the pressure drop of a bladder trap.

[crispy_wafer]

Todays addition to party was a grant 250l pre plumbed cylinder, should be with us next week.  I figured this would be a wise choice for us.  Got a plumber lined up for some evenings and weekend work to help with the install.

Edited March 16, 2023 by crispy_wafer

[crispy_wafer]

Just updating as i've gone quiet on this lately, slowly accumulating parts for the install

 

A couple of retailers have failed on the pre plumbed cylinder that I wanted, think there must have been supply chain issues, so have bought a 250l unit off ebay, as link listed in the marketplace.

 

Costs so far.

Grant 6kW Heatpump - 1280

Rubber Feet - 40

WH 250L Cylinder - 740

Primary pipework, press fit levers, press elbows, T's etc, caleffi antifreeze valves, pipe insulation, flexible pipes - 400(ish)

Grant buffer/llh - 325

Grant wiring centre ep001 - 40

Grant Hot water boost kit - 70

Mag Filter  - 100

 

Waiting for the cylinder to turn up now, so what's needed re: expansion/filling etc.

[ProDave]

Keep us posted.  So £3000 for all the parts.  It would be interesting to get a feel for how many hours it takes you to install it all when you do it.

[JohnMo]

For a filler I used the brass assembly at the bottom of the silver vertical pipes.

Fill and Flush Valve - 28mm from BES about £55.  Worked well.

 

For expansion you need to check if one is already installed in the ASHP, but possibly not.  So you will to size based on system capacity. I used an arm coming out of the wall, which had all the control stuff and bleed already included.

Flamco - Contra-Flex Heating Expansion Vessel 12 Litre FCST 012

Tesla T-BAR Expansion Vessel Fixing Bar Kit (T-BARKIT) from unvented components £60 delivered for both.

 

For the 3 way diverter I used eBay, plenty of good deals on there.

 

 

 

[Jenki]

9 hours ago, crispy_wafer said:

Waiting for the cylinder to turn up now, so what's needed re: expansion/filling etc.

@crispy_waferMy tank came with the expansion vessel, although he didn't think it did. So although I've not unpacked it I think you will get everything you need with the cylinder🤞

Comes with the 3 way valve.

If I get chance tomorrow, and can get to it I'll take some photos of the 210l

Edited May 15, 2023 by Jenki
More details

[BillO]

On 14/03/2023 at 14:04, crispy_wafer said:

So, I managed to bag a small Grant ASHP which I intend self installing, as much as I possibly can.

 

It'll be a relatively simple system comprising DHW and UFH, Spark and plumber will be doing the wiring and cylinder for me.

 

So getting stumped at the first hurdle, as I start looking for other bits needed for install... 

Although I'm a bit hesitant to ask questions as it shows my lack of knowledge somewhat, here goes the first few questions to enter my head..

 

How would I size the pipework from the ASHP to the UFH manifold, is there a rule of thumb?

The UFH has a design flow rate of 16.4 l/min, and the manifold is a max of 10 metres away from the heat pump.  5 bends at the most as the pipe goes up round and down! 

 

How do you decide if a buffer is needed? 

UFH Design volume is about 96 Litres this is a ground floor system, and all the loops are in rooms which will be used frequently so I'm happy to have the system act as a single zone.

 

Pumps?

Should I rely on the ASHP pump solely, or wire up the UFH pump too, then would I need to have a LLH, or is this a case of check the pump on the UFH circuit and see if it closely matches with the pump settings on the ASHP?

 

Cheers

Marek

 

Hi Marek

Did you manage to get the grant directly rather than via an installer? And, if so, How?!

Thanks in anticipation.

Bill

[crispy_wafer]

Ebay, from an MCS installer who had done calcs wrong for a customer, looking to get some money back, so, based on that I was happy to take the risk.

[crispy_wafer]

So, not much has happened with my install bar thinking about installation schematics and the possibility of how best to incorporate a 3 rad circuit for the bathrooms without compromising too much efficiency?  I was always set on having dual fuel towel rads anyway, so that option is available in the months where it's too warm for central heating, but we are still in goose bump territory. 

 

So, I'm thinking I should at least put the pipework in place should it be needed in future so the Rads can be installed on a point 2 point basis from a manifold and convert from 16mm to 15mm at the radiator. 

 

Control wise, I think running the ASHP for this would be wildly inefficient, so could I put a zone valve in place on this circuit and open this when the UFH stat downstairs calls for heat?

[sharpener]

20 minutes ago, crispy_wafer said:

 

So, I'm thinking I should at least put the pipework in place should it be needed in future so the Rads can be installed on a point 2 point basis from a manifold and convert from 16mm to 15mm at the radiator.

 

Eh?

 

22 minutes ago, crispy_wafer said:

Control wise, I think running the ASHP for this would be wildly inefficient, so could I put a zone valve in place on this circuit and open this when the UFH stat downstairs calls for heat?

You have conflicting requirements, the UFH will want a low temp and WC, the bathroom rads and cylinder high temp and no WC.

 

So how about programming the rads to come on mornings and evenings 30 mins before you are going to want to use the bathrooms and heat the DHW at the same time? (Works well with our gas boiler.) IIRC Grant recommends S-plan setup so that would be easy to do. This will help prevent short-cycling under low load too.

[JohnMo]

We just have electric radiators in the bathroom to supplement the UFH for towels. Didn't bother with piping them up.

[JoeBano]

I have a smart towel radiator in our bathroom, helps when the heating it off to dry towels. It also has a feature to come on when it’s reaches a certain temperature outside, I have it set to -2 just give us a help in winter. I do have wet Ufh as well though. 

[eniacs]

On 15/05/2023 at 09:14, crispy_wafer said:

Just updating as i've gone quiet on this lately, slowly accumulating parts for the install

 

A couple of retailers have failed on the pre plumbed cylinder that I wanted, think there must have been supply chain issues, so have bought a 250l unit off ebay, as link listed in the marketplace.

 

Costs so far.

Grant 6kW Heatpump - 1280

Rubber Feet - 40

WH 250L Cylinder - 740

Primary pipework, press fit levers, press elbows, T's etc, caleffi antifreeze valves, pipe insulation, flexible pipes - 400(ish)

Grant buffer/llh - 325

Grant wiring centre ep001 - 40

Grant Hot water boost kit - 70

Mag Filter  - 100

 

Waiting for the cylinder to turn up now, so what's needed re: expansion/filling etc.

Crispy where are you finding these parts for so cheaply - even the caleffi valves on ebay cost £75 each. 

You are also lucky to have such a cheap wiring centre - my mitsubishi has just cost me £750

 

I did manage to get the mag filter for £60 though, did you manage to get a "Heat pump filter" i had to send back the first one as it was too restrictive.

[crispy_wafer]

6 minutes ago, eniacs said:

Crispy where are you finding these parts for so cheaply - even the caleffi valves on ebay cost £75 each. 

Ebay, and patience (which is difficult for me), I don't need to install it 'next week' so am picking up bits as and when they pop up.  The caleffi valves I paid 80 ea for.  I need to get a zone wiring center.  Heatmiser uh4/8 i think.

 

I've got the grant buffer/llh to sell on, and the grant mag filter as the cylinder I purchased has a 50l buffer underneath and a mag filter attached...

 

There's the cylinder.

 

and that's the drg I'm working to, but now without any rad circuit, and probably not a secondary pumpset - we'll see!

 

[eniacs]

Nice diagram, ive not really worked to any diagram yet!

 

What's the flow setter for? Why would you not just want full flow and turn the pump down if its too high?

I've negated the isolation valves at the pump as i couldn't see the point in them. Surely these will only be used when the unit is replaced which hopefully isn't often.

Also haven't got a automatic air vent, not sure if that's essential either, i usually just vent the radiator at the highest point.

 

[crispy_wafer]

Just now, eniacs said:

Nice diagram, ive not really worked to any diagram yet!

 

What's the flow setter for? Why would you not just want full flow and turn the pump down if its too high?

I've negated the isolation valves at the pump as i couldn't see the point in them. Surely these will only be used when the unit is replaced which hopefully isn't often.

Also haven't got a automatic air vent, not sure if that's essential either, i usually just vent the radiator at the highest point.

 

 

It's from the Grant guide, it's the one that closely resembles the plumbing on my cylinder with a 3 port diverter valve and buffer, I'm not competent enough to draw out my own diagram from scratch, however from what I've seen most are similar in that they work on either the premise of a 3 port valve, or a couple of two port valves with logic to decide hot water or heating.  The flow setter, from what I understand is there to ensure an acceptable temperature differential between flow and return.  So yes you could adjust the in in built pump via the dip switches and the addition of the flow setter may be to give a more finer control?

 

 

[Jenki]

1 hour ago, crispy_wafer said:

 

It's from the Grant guide, it's the one that closely resembles the plumbing on my cylinder with a 3 port diverter valve and buffer, I'm not competent enough to draw out my own diagram from scratch, however from what I've seen most are similar in that they work on either the premise of a 3 port valve, or a couple of two port valves with logic to decide hot water or heating.  The flow setter, from what I understand is there to ensure an acceptable temperature differential between flow and return.  So yes you could adjust the in in built pump via the dip switches and the addition of the flow setter may be to give a more finer control?

 

 

Nice cylinder 😜, I've not un-packed mine yet as there's no house😁, Just for your info, you will need to install a two port valve as well to comply with unvented cylinder regs.

You can't just have a 3 port valve.

[crispy_wafer]

2 hours ago, Jenki said:

Nice cylinder 😜, I've not un-packed mine yet as there's no house😁, Just for your info, you will need to install a two port valve as well to comply with unvented cylinder regs.

You can't just have a 3 port valve.

👍 A 2 port valve to allow flow to the ufh like the schematic or somewhere else not shown on the schematic?

[Jenki]

16 minutes ago, crispy_wafer said:

👍 A 2 port valve to allow flow to the ufh like the schematic or somewhere else not shown on the schematic?

For the cylinder. You need a 2 port if the max thermal cut out stat is tripped. 

A quirk, but if you have a 3 port you still need a two port to act as a dead stop.

All unlikely with a heat pump, but thats the regulations.

[sharpener]

On 15/06/2023 at 18:26, Jenki said:

For the cylinder. You need a 2 port if the max thermal cut out stat is tripped. 

A quirk, but if you have a 3 port you still need a two port to act as a dead stop.

All unlikely with a heat pump, but thats the regulations.

 

Can you provide a reference for this @Jenki?

 

On looking here I can read the following

 

 

But i cannot find here or in the subsequent paragraphs a specific requirement for a two-port valve. A three-port valve which defaults to CH will meet the requirement in para 3.31 for it to fail-safe in the absence of an electrical supply.

 

However neither type of valve will meet the requirement for a non-self-resetting safety device so how is that achieved in practice? My unvented tank has got this feature, but only for heating via the immersion heater, not via the boiler and coil.

 

BTW it would seem that a G3 certificate is not mandatory provided you have the "necessary skills" and notify Building Comtrol before starting the work (as under) and on completion of commissioning (para 77):

 

 

 

Edited June 18, 2023 by sharpener

[Jenki]

1 hour ago, sharpener said:

 

Can you provide a reference for this @Jenki?

 

On looking here I can read the following

 

 

But i cannot find here or in the subsequent paragraphs a specific requirement for a two-port valve. A three-port valve which defaults to CH will meet the requirement in para 3.31 for it to fail-safe in the absence of an electrical supply.

 

However neither type of valve will meet the requirement for a non-self-resetting safety device so how is that achieved in practice? My unvented tank has got this feature, but only for heating via the immersion heater, not via the boiler and coil.

 

BTW it would seem that a G3 certificate is not mandatory provided you have the "necessary skills" and notify Building Comtrol before starting the work (as under) and on completion of commissioning (para 77):

 

 

 

From my G3 course,

Bottom paragraph in bold. This was a BPEC course.

 

[Jenki]

1 hour ago, sharpener said:

BTW it would seem that a G3 certificate is not mandatory provided you have the "necessary skills" and notify Building Comtrol before starting the work (as under) and on completion of commissioning (para 77):

 

 

 

How will you prove you have necessary skills?

Similar to part P, if you do the DIY route expect an additional charge to get someone in to prove it's safe. BC will not take that risk.

 

The plumbing and theory of G3 is straightforward, but there are pitfalls and ambiguity, a lot based around D1 and D2 discharge pipes.

 

[JohnMo]

But does a Y plan not use a 3 port mid position valve that allows flow through to either or both CH and DHW, so never actually closes flow off all together. Where a heat pump valve flow can go to DHW only when energised. All other times it is directed to CH and in its failed state only directs to CH.

 

So in effect actually operates on the same principle as 2x 2 port valves, which is very different from a Y plan valve.