Poor hot water system.

[cdbe]

My brother lives in Scotland in a former farmhouse.

Old floor standing heat only boiler that appears to run well. There's a copper cylinder in a cupboard next to it, I think at about worktop height

Two bathrooms, both with electric showers, downstairs has a bath. We used the first floor bathroom when we stayed and the shower wouldn't heat when the dishwasher was running so presumably poor pressure? The hot to the upstairs basin was (badly) pumped - would the rest of it be? I think they bought one of those Argos bath tap showers for downstairs but it didn't work so maybe the ground floor is just gravity?

Before we visited and used the upstairs shower he said the mains pressure was good so I suggested an unvented might be the answer. Now I'm thinking an unvented with an accumulator?

I know he needs to check flow and pressure first, but assume poor, will this work? I think they're happy to invest in something that works properly.

 

[ericmark]

Question one has to be where does the water come from? I know here in Wales may homes have a well and a pump.

 

[cdbe]

A mains plastic supply pipe that runs over (or rather under) fields from a nearby farm.

 

[Madrab]

1st thing first, they need to find out what the mains dynamic pressure and flow is from the mains at peak hours, as it enters the property. Without knowing that then any advice would just be a guess.

If pressure and flow are poor then yes either correctly designed stored hot and cold suitably pumped. Mains pump may be an option or alternatively yes an accumulator (poss pumped) but that is space and finance hungry and doesn't deal with the HW. It would also be of benefit understanding if the mains is shared with the farmhouse as that could have a direct impact on what may be available.

Where in Scotland are they?

 

[cdbe]

Thanks. I'll get them to check pressure and flow and establish the source of the supply pipe. It's Cruden Bay, near Peterhead.

 

[Madrab]

Cruden Bay, near Peterhead

Lovely part of the world, fab beach and a great links course.

 

[fixitflav]

Old floor standing heat only boiler that appears to run well. There's a copper cylinder in a cupboard next to it, I think at about worktop height

Is there a cold water storage tank (CWST)? Most likely in the loft.
Is the system fully pumped on the primary side, or gravity to the HW cylinder? Are there any motorised valves?

The hot to the upstairs basin was (badly) pumped - would the rest of it be?

The pump would be on the secondary side. Whether the rest is pumped depends on where the pump is.
A sketch of the system would be useful

 

[cdbe]

The cylinder is actually on the floor, so presumably all the HW is pumped. He's ordered a pressure gauge and he's going to establish pressure and flow in the first instance - the closest he'll get to the incoming main will be the WM tap in the utility but hopefully will give a reasonable indication. He said there's a small tank in the top of the loft (presumably a header for the heating). We're visiting next month so I'll investigate further.

 

[cdbe]

Pressure is 2 bar at outside tap, dropped to 1.8 when kitchen tap turned on. Flow rate about
4 l/min.

The pump does all the hot water taps.

This is the business end:

 

[Johntheo5]

Can you post a clearer view of the Pump details or if you can read them just post the details.

The cold flowrate is 4.0LPM at a dP of 0.2bar, 2.0/1.8bar. You probably need at least 8LPM and preferably 10LPM when mixing with cold, if a shower then the mixing will take place at the lowest of the hot/cold, at a cold flow of 8LPM, the dP is 0.8bar, pressure 1.2bar. At 10LPM, the dP is 1.25bar, pressure 0.75bar, maximum mixing pressures, 1.2bar at 8LPM & 0.75bar at 10LPM, IMO.

 

[Madrab]

If the mains is 1.8bar with one outlet open but the flow rate is 4L/Min then there must be a restriction in the supply somewhere. If the dynamic pressure is 1.8bar then the supply should be delivering much more than 4L/Min, unless the supply is on an excessively long run of 15mm pipe. If the supply is MDPE (20/25/32mm) then there has to be a restriction upstream somewhere.

The pump looks like a Grundfos single ended 2 bar universal (negative) shower pump (plastic impeller). If that's for the hot water then the HW cylinder would normally be gravity fed but can't see the cylinder. Wouldn't ever expect to see an unvented on a supply @ 4L/Min.

If nothing else can be done then an accumulator may be the answer. Expensive solution though.

 

[cdbe]

I've told them to call Scottish Water to do a free check. No idea about size of supply pipe but he's spoken to the local householders who've said he's the last house on the supply. Also they have meter which I suppose will need checking, but they pay for water through their council tax (Scottish system) so don't know why.

We repressurised the heating circuit last night after changing some radiators - took a while to get to 1.5 bar.

Assuming nothing can be done about the supply then an accumulator (and maybe a charging pump?).

Would that just supply the cold with the pump retained for hot?

I don't think the cost is a issue but obviously it will need to work.

 

[denso13]

Also they have meter which I suppose will need checking, but they pay for water through their council tax (Scottish system) so don't know why.

You can opt for a meter and only pay for what is used.

 

[cdbe]

You can opt for a meter and only pay for what is used.

I believe so, they're new to the house since last November and told me it's on the council tax but I don't know whether the meter was used historically and (unlike UK) people can swap between?

Edit - the supply comes from a farm about a mile up the road to their cluster of 3 houses, the meters are so the the water used by the houses can be "knocked off" the farm's bill.

 

[Exedon]

Edit - the supply comes from a farm about a mile up the road to their cluster of 3 houses, the meters are so the the water used by the houses can be "knocked off" the farm's bill.
[/QUOTE]
That explains much.
Living out in country over years we have up graded a number of properties with exactly same problem.
Dependant on property some break tanks and pumps
Others accumulators one over a mile from supply originally 1/2 in lead we replaced with 63mm MDPE.
Owner of that property did own the woods between house and main road and a Jcb.
.