Notifications

Clear all

[Solved] Hot water issue, never seen this before: Grant Heat Pump and Cylinder

Page 1 / 2 Next

Domestic Hot Water & Cylinders

Last Post by Marvinator80 2 years ago

14 Posts

5 Users

7 Reactions

3,301 Views

RSS

Marvinator80

(@marvinator80)

Honorable Member Member

Joined: 3 years ago

Posts: 201

Topic starter 21/01/2024 11:01 pm

This is so weird. Cylinder is heating up fine. Temp says 53 right now. But when I run the cold tap it’s hot only for a short period and then cools down very quickly so I have lukewarm water at best.

Anyone ever had this?

Baffled of Ayrshire

Quote

Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 3427

23/01/2024 12:04 am

Any updates on your situation?

Pre-order: The Ultimate Guide to Heat Pumps

Subscribe and follow our Homeowners’ Q&A heat pump podcast

ReplyQuote

Marvinator80

(@marvinator80)

Honorable Member Member

Joined: 3 years ago

Posts: 201

Topic starter 23/01/2024 8:52 am

Posted by: @editor

↑

Any updates on your situation?

not yet. It did resolve itself for a while yesterday but is back to the same issue now.

We have had water pressure issues in the area due to power outages affecting pumping stations but I just don’t know. Our plumber was too far away yesterday to come but hopefully will come today.

ReplyQuote

HughF

(@hughf)

Noble Member Member

Joined: 3 years ago

Posts: 489

23/01/2024 12:14 pm

do you have a blending valve (TMV) on your hot water supply from the cylinder?

Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.

My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.

ReplyQuote

iancalderbank

(@iancalderbank)

Noble Member Contributor

Joined: 3 years ago

Posts: 643

23/01/2024 12:36 pm

Are you sure you've describe it the right way round? Your description says the cold tap runs hot then lukewarm? Did you mean the hot tap? If so then either there's not enough hot water in the cylinder or something is blending in cold when it shouldn't be, such as a TMV.

If it IS the way you described it please confirm.

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs

ReplyQuote

Marvinator80

(@marvinator80)

Honorable Member Member

Joined: 3 years ago

Posts: 201

Topic starter 23/01/2024 4:39 pm

@hughf I would expect so. It’s a Grant pre-plumbed cylinder and I do suspect the issue is with blending.

I’m waiting for plumber to take a look now.

ReplyQuote

Marvinator80

(@marvinator80)

Honorable Member Member

Joined: 3 years ago

Posts: 201

Topic starter 23/01/2024 4:41 pm

@iancalderbank yes, that’s right Ian. I mistyped in my opening post. It is the hot tap. Runs, gets hot and then quickly becomes lukewarm when I know for a fact there is plenty of hot water in the tank.

👍

ReplyQuote

iancalderbank

(@iancalderbank)

Noble Member Contributor

Joined: 3 years ago

Posts: 643

23/01/2024 4:44 pm

Posted by: @marvinator80

↑

@iancalderbank yes, that’s right Ian. I mistyped in my opening post. It is the hot tap. Runs, gets hot and then quickly becomes lukewarm when I know for a fact there is plenty of hot water in the tank.

ok no worries . in which case I concur with yourself and hughf, blending valve is the first place I'd check. you should be able to feel the temperature of its 3 ports change over time as you run the water.

👍

ReplyQuote

Marvinator80

(@marvinator80)

Honorable Member Member

Joined: 3 years ago

Posts: 201

Topic starter 23/01/2024 5:01 pm

Thanks everyone. I’m not sure what the blending valve looks like on the grant set up. I guess a plumber will know. 😬😬😬

ReplyQuote

iancalderbank

(@iancalderbank)

Noble Member Contributor

Joined: 3 years ago

Posts: 643

23/01/2024 6:06 pm

@marvinator80 its not a grant specific component. Find the hot water output pipe coming out the cylinder and follow it.

something like this

👍

ReplyQuote

Marvinator80

(@marvinator80)

Honorable Member Member

Joined: 3 years ago

Posts: 201

Topic starter 23/01/2024 7:06 pm

@iancalderbank I can’t see anything like that. This is the bit where the water seems to mix, but I’m not sure. I guess if that’s faulty it will need replaced. Trying to gently hurry up my plumber.